ptumbi I quite agree - grabbing anyone in that way is unacceptable, but in front of friends and passing it off as humour?!
OP, I'm glad you're reviewing the situation. It is not normal. This is not how normal men behave. In fact, the last time I encountered anything vaguely like this was about a hundred years ago when I was at school (well, it was in the 80's) and the boys in my class aged 12 & 13 thought all women were just walking boobs and bits.
If you think he'd listen, you could tell him that you don't like it when he grabs you when you're in public. Tell him it is embarrassing and degrading. Tell him if he does it again you'll shout and make a fuss. God knows I would be screaming at the top of my lungs if my OH tried that on me. And punching him in the groin
If he won't listen then there is little chance things will improve, which, from what you've said before, seems to be the case.
This is not a healthy relationship. This does not set an example for your daughter. I wonder if you call Women's Aid if they can advise you on best way forward? If you're not in danger of violence I can understand why you're reluctant to pursue this sort of action, but assault is still assault. Ideally you can go and stay with your Aunt for a bit whilst you sort things out.