This may shock everyone, but it's stated in Isaac's description that he actually has no issues controlling himself or his nature. It's generally well known around the school that his flirtatious nature is almost completely harmless and he doesn't actually sleep with that many people.

I noticed that a lot of people have been talking about his reputation, it is actually rather non-indulgent. And there is a reason for this. *stares pointedly at Major Ursa*

Also, Ajala is adorable.