Possible problems in the future between my boyfriend and I due to cultural differences?

I'm an aussie, and he's from Zimbabwe. Everythings going great, except that his parents, or his stepmum anyway doesnt really seem to accept me. It's very awkward between the two of us when i go over to my boyfriends house, and if i ever come over uninvited (despite the fact my boyfriend and I have been together 5 months) my boyfriend gets in trouble for it.. I'm just wondering if anyone here has any advice etc from past experiences or stories they've heard from friends in the same situation etc.