Let me draw a parallel between these two couples and explain why.

Destiel is all about long stares, standing too close to each other and holding in hugs for longer than necessary.

But the ineffable husbands, them, are all about 'little demonic miracles', eating together at a fancy restaurent and recalling all their history together.

Destiel represents love, but the kind of love that you don't understand. Dean doesn't understand why he's attracted to Castiel. All his life he had loved only women and now he's attracted by a guy, he doesn't understand it.

Cas, it's the very concept of love that he can't get a grip on. For most of his life, he was an emotionless soldier, then he fell in love with Dean. He didn't know love, he didn't understand what was happening to him. We see him evolve and learn new emotions throughout the series and at the same time understand his love.

They don't know that the other loves them and are too scared of rejection and losing their best friend to make a move.

But the ineffable husbands, it's in their name, they know they love each other and more importantly, they know that the other loves them. Crowley knows jus how much he means to Aziraphale and vice versa.

It's when Aziraphale refused to give Crowley holy water in fear that he wanted to kill himself, but gives it to him when he understands Crowley's motivations.

It's every time Crowley saved Aziraphale's ass, fixed his coat and saved some of his books. It's when he speaks of running away together, running from the apocalypse together, to be together forever.

By the way, in the book, it's said clearly when Aziraphale is described that he would be labelled as gay. Just leaving that there.

Destiel and the ineffable husbands are polar opposites. Destiel is love when you're pinning on the other without knowing that the other does the same.

The ineffable husbands are past that stage. They are a couple and would do everything for each other, but most importantly, they know that the other loves them just as much as they love him.