What should i do about s fifteen year old boy who lives wit me and his mom?

ok so his mom is movin to another part of ohio and he gets to live with me and my fiance till he graduates but he has to go visit his mom on weekends but he doesn't really like his mom or her boy friend. they got into an argument last night and now he is really mad. i know its prolly none of my business but he is unhappy! plus she hasn't exactly been the best mom ever too! so idk if i should say something or not please help!