I want to ask my boyfriend to stop wrestling with the dog because it was weird
They're just having fun. Why is wrestling with the dog so weird to you?
Because my dog is a female. I don't want to see him being so intimate with a female dog.
It's just a dog, not a human. You shouldn't tell your boyfriend what he can or cannot do. Your overreaction could lead to a break up.
I am pushing him to be less touchy with the dog.
I think you should rather encourage touching the dog... it's a way dogs know they are loved by all the cuddles and playtime. How is your dog going to feel when everyone suddenly stopped playing with her like that? Your boyfriend can do whatever he want, it's his dog too.