Maybe a little more choice during the party depending on stats and / or decision made previously. Not really my kink (just like to test "everything" :p) but, "real" fun with the bros, kinkier action with sister...
Once again, maybe you plan it for later and make it a slow burner wich is fine... just feel kind of strange that MC would masturbate to gay porn with toy up inside but still be like 100% straight (and yes, I know position doesn't imply orientation but still...).
And since we can make MC on the submissive side, with weak stamina and high arousal, maybe some "confrontation" feels a little odd too (why even try to confront with girlfriend's dad ?) and again it may be plan for later, but some humiliation talk ?