Jongwoo:

If he could buy it, he wouldn't be living in a shitty apartment! Walking in this store is more just a hangout walk area than an actual shopping area. So you can join him in the staring at items, wanting them but knowing damn well if you get it you'll fall in debt as you won't be able to pay the rent.

Moonjo:

This man is RICH! He is a dentist, doesn't spend much, and lives in a shitty place so his rent is also little. His money stacks up.

Meaning if he sees you like something he'll go get it for you right after bringing you to your destination. Then next visit he'll have the gift in hand in a pretty bag or wrapping.

Junghwa:

Now she is determined to save up and get this item for you! Or she might just encourage you to buy it yourself as treating yourself is also important. But the former is always more fun, and makes her feel like an amazing girlfriend making up for any possible mistakes made the past few days.