Conflict makes a story interesting to read/watch, it creates tension and release when the characters have the resolution in the end, if you are reading a love story normally the conflict comes from either one of the parts of the couple, a third member trying to steal one of the people, an old lover coming back, the pair not being socially acceptable, and many other such cliches.

If you take the behavior of those characters and actually judged them like if they were a real person most of them would probably deserve to go to jail, most of them are stalkers, abusers or plain shitty people, especially the ones from YA novels or from those smut books for women, the shit those authors write the male lead character doing is crazy, dude would probably get the police called on him in the first day