Dude. All you need to ask is why do you read yaoi. You are making quite alot of assumptions that are not true. After asking this one question you will see most of your assumptions are just irrelevant and also something that I have, personally, never even kind of thought. Oh yeah, also, I guess I have to outright say this since you seem to believ......
Manga's purpose is entertainment, it doesn't have to be realistic, so of course it's different from real life and how gay relationships actually develop but that's what's fun about it, the unusual events and the drama that normally doesn't happen in real life is what attracts the reader to the plot. If you personally hate those kind of things then ......
5 Question for fujoshis from a gay guy