You might need to be the bigger person here. I'm not saying you can't have a real relationship with that large of an age difference. But your priorities are totally different. He's found his life and you're just now starting to find agency.
I would advise keeping things just as they are until you know where you're going with your life. I've never seen a thirties / college age relationship end in any other way than a break up. Keep it light and non-committal so when it does become obvious that you can't stay with him, it won't be too hard.
If he can't handle waiting a few years for an uncertain outcome, he really shouldn't be dating 19 year olds. A man in his mid thirties is generally looking for the one thing you can't give him, at least not yet. Marriage.