Maybe it's entitled to think that everyone has good familial relationships where such things were learned.

Newsflash. They don't. Lot of people grew up in dysfunctional families, deep poverty, broken communities, etc.

Good, healthy relationships weren't available to them.

They have to learn from other things and other relationships. You make friends in college and learn from them. You learn from your professors and TAs. You learn from mentors. You learn from the places you works the people you work with, and the people you meet there.

You learn by doing life, in other words.

Then, when someone comes along who's a keeper, you gained the skill set unavailable to you in childhood so you don't muck it up.

But you have to have been investing in that learning process for yourself.