I don't know if I should tell you this, or how to tell you this but this is a GAME, not real life.
Derek is there on that moment, for collecting data about the player decisions.
but to properly answer, I need to know Derek response if you say you are interested in Josy,. He can easily see in that way, if Josy is willing to break up with Maya for somebody else, then Maya is better off without her, But Derek, not intervening in Maya relationship to much, both Maya and Josy, cheated, an they forgiven each other. It does not mean it can't have consequence for the MC and Derek relationship. but Derek pretty much know the whole story, he is in a tough position, so it's more than likely He stay out of it.
if MC dating Maya, and then cheat on her or hurt her in anyway , now that is a difference story, where Derek can hold accountable the MC, but for Josy's actions, he can't hold the MC responsible, in that scenario its Josy who eventually hurt Maya. Derek can easily see from this perspective. More or less, because he also know the History, between Josy and the MC.