On Wednesday morning, Diana's side of the bed is cold when I wake up. I can hear her in the kitchen. A glance at the clock tells me it's still fairly early, but I push out of bed and grab a towel for the shower anyway.

While I'm in there, she knocks on the door and calls, 'Will you be long?'

'Not really. Why?' But there's no answer, and I think she's moved off already.

Slightly worried, I finish up and dress hurriedly, fumbling the buttons on my blouse and having to straighten my skirt properly on my hips as I head through to the kitchen. Not having bothered to dry my hair fully, I can feel a few drips slide down my back inside my collar. I've also nicked my shin slightly while rushing to finish shaving, much to my irritation. 'Bathroom's free,' I say, assuming she needed it after me, although she's already dressed and seemingly ready. She shakes her head and sighs. 'What's up?' I pad across to the coffee machine and pour myself one, before pushing two slices of bread into the toaster.

'I was hoping to get an early start.' She sounds very slightly irritated.

'Sorry. You should have said.' I glance at the clock. It's more or less the normal time we'd start having breakfast. 'I'm sorry I'm not very good in the mornings.' I go back into the bedroom and towel my hair furiously for a minute, then head back out with my hairbrush.

She watches me brush my hair, then shakes her head again and smiles. 'Sorry, Fiona. I didn't mean to be tetchy.' She comes over and strokes my arm. 'I like that blouse, by the way. It suits you.'

'Thanks.' I like it too, it's pale blue and soft and manages to be both comfortable and smart, with a slight hint of sexy. The toast pops up and I slide it onto a plate while she gets the spread out of the fridge and hands it to me. I lean up on my toes (in bare feet I am quite obviously several inches shorter than her) and kiss her lips briefly.

She responds, but I know we don't really have time and break it off. I turn round and start to butter the toast. I can feel her eyes still on me. The skirt I'm wearing is the cute miniskirt I had on by chance that time we kissed properly at work, a week or so into seeing each other, and my legs are still bare and freshly shaved. I wonder if that's what's catching her attention (cut notwithstanding.) She gives one of her soft little happy grunts and tries to sound off-hand. 'That skirt's nice, too.'

I smile to myself and cut the slices of toast in two, pushing the plate along the top towards her. 'Nice, is it?' I pick up my mug of coffee and blow on it, then take a sip. 'Glad you like it.'

She steps closer behind me, pressing herself lightly against me, and runs the back of her hand over my hip. She nuzzles my neck again. 'Mmm. Nice.' She turns her hand and slides it over the curve of my bum for a moment, between us, where her crotch is pressing against me. She kisses my neck lingeringly. 'In the sense of insanely sexy.'

I hold my breath. There's a moment, a throb or two of arousal between us, where the spark threatens to catch. But she draws back. I brush my hair away from my neck, trailing my finger over the patch where she's just kissed me. 'Ah, OK. That kind of nice.'

We smile at each other, and the moment turns into one of shared affection. I watch her bite into a slice of toast and think how much I like the way our senses of humour match so well, how easy we feel with each other – and have done since really quite early on. I like the way we instinctively seem to understand each other, have become close as friends as much as lovers. I like how it feels, practically living together this week, and have a little pang of regret at the thought of going home again.

Diana pushes the toast towards me after taking another slice. 'You know, Fiona, it feels strange having you here like this.'

'Strange in the sense of insanely sexy?' I raise an eyebrow. "Strange" isn't quite how I'd hoped she might feel about it. It's a bit different, certainly, but I like it. It makes us feel even more like a real couple.

She smiles. 'No. Just strange.' I must look a bit disappointed, because she wags a finger at me. 'Not in a bad way. It's just odd for me, that's all. Are you going to the gym tonight?'

'What? Um.' I'm still wondering what she means by "strange" when I was just thinking how nice everything was. A tiny little niggle of wariness makes itself uncomfortable at the back of my mind. I'm suddenly not quite sure where the conversation is going. 'Probably, yes. Why?'

'Well, it would be helpful to know. I'm not, this week, I don't really feel I can, so that might change what we do after work.' She sips coffee and looks at me seriously. 'It's having to consider this kind of impact on domestic arrangements that I'm talking about. It's not something I'm used to.' She glances away and frowns. 'Not these days, anyway,' she adds, half to herself.

'I can walk back. It's OK.' I turn away and take a gulp of coffee, and catch sight of the time. I put my mug down. 'We should go soon. I need to finish getting ready,' I mumble, moving past her quickly. I do need to finish getting ready, but I also now feel slightly awkward. It occurs to me that maybe by inviting myself round for the week, I've been quite selfish – just because I want to spend as much time as possible with Diana, and enjoy looking after her, doesn't mean she doesn't see me as being under her feet or fussing around her while she's busy and trying to get on. Especially in this run-up to her case and her speech. Perhaps by trying to be helpful, I've been anything but. Suddenly, I worry that perhaps Diana is just tolerating me being in her flat.

***

The drive in is quite quiet. Diana tuts in frustration as we sit in a patch of heavy traffic, and I feel guilty about not getting up earlier. The traffic moves, but we get caught as the lights change to red. She 'hmph's and puts the handbrake on, but then rests her hand on my leg, stroking my knee absent-mindedly through my tights as we wait. I apologise out loud for making her late, and she squeezes my knee.

'Don't worry, Fiona. I'm sorry I was cross.' Her hand strays onto my thigh for a moment, before the lights change and she has to put the car in gear again.

During the last of the drive in, I ponder the status of our relationship. Now that Diana and I are together and have been for a while, and we both seem to be treating it like an on-going, long-term, thing, I realise I must have assumed that we could slowly start to blur the lines between our separate lives. I mean, on the one hand, we have been spending a good deal of our free time together, and it's been rare these last few weeks, maybe even months, that either one of us will do something major in our free time without the other.

When we decided I should spend the week at hers, I assumed it would just be like being there all weekend with breaks to go to work – in that I'm the more domestic of the two of us anyway, and I'm quite capable of amusing myself in her flat while she's busy. And we're not having noticeably any more or less sex than usual, making allowances for the fact that there's just less time on weeknights, so it hasn't changed an awful lot there. I had assumed she'd probably be thinking twice about the gym tonight, but I saw no particular problem in going by myself and finding my own way back to her flat afterwards, so it had never occurred to me until now that she might be worrying about the logistics of it.

Things have been turning out to be different during the week, though. It does feel different to be with her in the flat on a workday. It's different to feel her slip out of bed while I'm still drowsy, and know that time is pushed like this morning. And there's a different routine. This morning, when we didn't deliberately wake up early, it was clear that normal weekday life was different from weekends. There was no time this morning for lounging together in bed and I had to pretty much get straight up. I feel a bit guilty if I've made her twitchy about the time, but she knows I'm not as good as her in the mornings - and to me it felt nice to be so normal in a comfortable domestic way. Perhaps it was that feeling that Diana had meant was "strange".

Perhaps I know what she means, in that being together in the week makes it very clear how often sharing your space with someone else means making little efforts to accommodate their quirks. I'm used to it, always having shared with someone through university and now with Paula; it must be strange for Diana, though, who's lived by herself for so long. I do hope it won't be too much of an issue for the rest of the week.

***

A little way through the morning, I get to a boring bit of work and my little niggling wariness hasn't gone away, so I email Michelle and tell her I'm available if she wants a cigarette break.

She replies about ten minutes later, to say she's on her way down. We meet in the foyer and push through the door to the smoking shelter.

'So, babes,' she asks, lighting up and exhaling smoke happily. 'What's new?'

'I'm spending the week round at Diana's, did you know? Looking after her, while she's putting in the hours on that case you've got coming up.'

'How very domesticated.' She grins. 'Let me know when you've set a date.' I must look puzzled, because she adds, 'For the wedding. Civil partnership, whatever.' She grins again at my expression of surprise. 'It's a slippery slope, isn't it? Spend a few days there in the week, find you're leaving more and more of your stuff there, move in properly...that's it then. May as well go the whole hog.' She links her two little fingers in a gesture of union, and drops ash on her trousers.

'You're such a romantic, Michelle.' I sigh. 'It's not like that at all.'

'Cut me and I bleed little red hearts.' She brushes the ash away and looks at me carefully. She knows me well enough to be able to tell that I'm fretting about something. 'What's the matter. I'd've thought you liked feeling all domesticated, making sure she eats and all that.'

'I do.' I shrug. 'I don't mind that at all. I like cooking for her, and I'd only be doing it for myself anyway, so it makes sense to be round there instead.' I sigh again. 'I dunno. It's just a bit different through the week, it seems. She's different through the week.'

Michelle looks at me for a moment or two, then asks, 'Is it the sex, Fi? Not the same as it was?' She waves her cigarette up and down me. 'Hence that skirt. Trying to remind her what she's missing, eh?'

I self-consiously try to tug the skirt hem down a bit. 'No, no. God, no. That's all fine. I mean, I know there's less time in the week, and anyway, yesterday we had a really nice...'

'And stop there, Fi.' Michelle holds up a hand. 'I don't need to know the details, babes.' She drags on her cigarette again and grins at me. 'Good, though. That that's still going well.'

I grin back. 'It's amazing, Michelle. All of it. Not just physically, though that's really good. It's the whole way we are together.' I wave my hand vaguely. 'It's...it's like it's something really deep, really...fundamental to both of us, to our very beings...'

'I thought that at that meal, you know? You just looked so good together, you are so good together. And you've had a miraculous effect on her temper, she's really quite a pleasure to work for, now. Nothing like the old Diana the Huntress, Goddess of the Office Fumble.'

'Good. And that night of the meal was really intense. But...I think she feels it too. I'm sure she does.' I think back to what she said at the weekend about feeling a connection, and to how I could feel how deeply moved she's been recently by what we have together. Suddenly, I wonder how she's feeling about that – knowing Diana, I expect she will not have wanted to be ambushed by these kinds of feelings.

Michelle goes on, 'I have to say, Fi, she's noticeably more relaxed these days. Still a bitch of a lawyer, but no longer the bitch of a manager she used to be.' She draws on the last of her cigarette, then jabs it at me with a dirty grin. 'Getting plenty off you must be helping.' She frowns lightly. 'Though if she's falling for you...well, she won't be used to that. She won't like it, I shouldn't think.'

'No. I've just thought something similar.' The niggling at the back of my mind begins to take shape: it would be good to know just what Diana does think about our relationship at the moment, and what she thinks about its future. 'Hmmm,' I say, mainly to myself. 'I think we need a talk, she and I.'

Michelle grinds her cigarette out and stands up. 'I'd say that's a good idea, and sooner rather than later. It's always good to talk about these things. Not that she strikes me as being one for that sort of talk, much.' She follows me in through the door and strokes my arm gently. 'Good luck, Fi.'

***

In the early afternoon, Diana sends me an email, asking if I'm free to go and see her. I finish up what I was doing and make my way upstairs. On my way, it occurs to me that although Diana and I are effectively an office romance – in that we met at an office party – we haven't really conducted most of our relationship here. I haven't set foot in her office for months now, and even if she comes and sits downstairs with me on a Friday these days, it's just for the company and we get on with our own things in companionable silence.

Sandra isn't at her desk when I get there, but Diana's door is open, so I knock and poke my head round the door. She grins and invites me in, getting up from her desk to greet me. The way she eyes me up as she walks towards me is unexpected, and rather blatant. I find it surprisingly arousing, and remember how just one of her glances could melt my knees when we first met. We kiss in the middle of the floor between the desk and the door, then she brushes past me and quietly closes the door. Then I feel her behind me and lean my head back against her as her hands go around my waist.

She kisses my hair. 'God, Fiona...you are so sexy.' One of her hands slides over my navel. 'That blouse, that skirt...I've been fantasising all day...'

I giggle. 'Really, now?' I like the fact she's turned on, but I'm still anxious that the air still isn't quite clear between us. She slides her hand up and cups my breast in my blouse, but I put my hand over hers to keep it still. 'Diana...I think we need to talk.'

She leans in and nuzzles my neck, and I feel the thrills pass though me despite myself. She knows doing that always gives me pleasure. She nudges me over to the sofa by the window, and we kiss again before sitting down. I perch on the edge, knees clasped together, but she lays one arm behind me along the back. Her lips are full and her eyes are bright, and she kisses me again quickly, letting her free hand drop gently onto my thigh. Unthinkingly, I move my leg a little and enjoy the way her fingers circle on the inside of my knee. I'm still unsure about giving in to the temptation, but equally I can understand how quite so many young women have ended up on this same sofa with her.

She's combing the fingers of her other hand through my hair and stroking my shoulder, and she buries her face in my hair for a moment. 'I am sorry about this morning.' Her fingers pull at my collar gently to expose more of my neck and she kisses it softly, running the tip of her tongue over my skin.

I feel the goosebumps rise on my arms as the pleasure trickles through me, and hold my breath. Her hand slides further between my thighs and I can't help letting them twitch a little apart as her fingertips brush the hem of my miniskirt.

She kisses my mouth again quickly, then nuzzles my ear and neck again. 'I just woke up a little tense.' She gently nudges me with her head on my shoulder, to lean back on the sofa, and I don't resist. She plants little kisses on my open throat, then moves her mouth down over my blouse to kiss the shape of my breasts.

It feels so good, and I sigh with arousal, slightly irritated at how I am unable to resist her. 'OK. I'll try and be better in the mornings, anyway...' I reach up and stroke her cheek while I push her head away and undo the top couple of buttons on my blouse.

'You're always good, Fiona. Any time of day,' she mutters excitedly, kissing the exposed skin at the top of my breasts, where I've partially undone my blouse. Her hand on my leg slides under my miniskirt, pushing more firmly between my thighs.

I lean back further and stroke her back, closing my eyes and letting the pleasure wash through me and drown everything else. It doesn't pass me by that I am only the last in a long line of girls to give into her like this, on this sofa, and that it is so ironic that it's only now - when we've come so far together – that we're doing this.

It feels wrong, sordid, in a way...but how can I resist her touch and her kisses? I can't pretend that I am not still desperately aroused by how much she wants me, or that I don't fancy her despite the niggling worry about where we are in our relationship. Or that the idea of doing it like all her other girls doesn't turn me on, because it does. It's so wrong, but so good too, not least because it is so very slightly sordid.