Have you tried playing on easy mode?
The game was originally not really intended as a dating game, so the relationships are often hard to maintain. But easy mode should make it play more like a regular dating sim.
(Adam is, of course, the exception to this. He was intended to be an extremely difficult bonus, so his popularity caught me a bit by surprise.. and as such, he's still extremely difficult even in easy mode.)
In general, the characters should give you pretty good indications when you're doing something wrong or not, and knowing their personalities should also help you make the right choices. Also note that your character has a "personality" that is established mostly by the choices you make when you're introduced to new people, and having the right personality makes it much easier to successfully date someone. (Jake, for example, is shy and gets along better with a shy protagonist.)