Because it’s not what most really want until very late in the game.

People want excitement, they want a fight or conflict in the way of who they’re attracted to, they want sexual tension and build up - not safe guarantees.

They don’t want predictable and stable. This is mundane it if you think about it. You have to remember up until people find that long lasting healthy relationship, those people have NEVER experienced that. By definition of not having found that long term partner, where it all works out and they build a life, its because all relationships so far up until that point, short and slightly longer, have failed for some reason.

I think sometimes when people are lonely or single for a while, or getting fomo when they see their friends in relationships, then they pine for it. But it’s not the overriding desire, hell, it’s the lack of the relationship that stokes the feeling of wanting it. Actually being presented with it and being able to have - stable, no drama, healthy - instantly makes a lot of people realise they don’t want it, so they disregard the option or sabotage, because deep down we’re not ready for our story to finish, the party to be over.