third DUI offense?

I've been dating this guy for a couple months now. He is 28 and I am 20. Sunday he was arrested for his third DUI offense and I'm not really familiar with all laws but I know that he will have to serve mandatory jail time. (BTW he has three kids and he still seems to only be living for himself) I am really stuck in between being here for him and leaving him for making such a dumb decision. I feel like the adult in this situation. I mean we are both adults but I feel like I'm teaching him how to be an adult when he should really be watching me blossom into adulthood. My question is do you guys think he is too old to still be going to jail for DUIs? And what would you do in this situation?