The trophies are awarded the first time you complete specific actions. They can only be awarded once for each play through. Playing the game again and completing that action with a different character will award a new trophy.

Some trophies are specific and not available for all characters.
Example: Not all characters are virgins, so sleeping with certain characters will not award that trophy.

Some actions can award multiple trophies. Losing your cherry to a MILF will award the trophy for losing your virginity, whilst also awarding a trophy for sleeping with your first MILF.

The Trophies App will display awarded trophies for the specific game you are playing. The main menu allows you to see which trophies you have accumulated through all played games.

Since the game is linear and released in stages it is expected most players will accumulate the same trophies, at least initially.