Forget probation-- it sounds like you need to drop his ass. Now, if you only saw each other once every three weeks, I could see where he might be feeling the need every time he sees you.
But there's still no reason to feel obligated to do anything you both don't want to.
[After marriage? Same thing. (Sheesh, I'd think most people would get sore-- I mean, if you see each other every morning and every evening and all day on weekends.. that's a lot of hooking up!)]