She was asking me how I'd like it if she was dancing with random guys holding her and stuff. She said I can keep doing it but she "knows what she'll have to do." I think it's obvious.

You could point out that if you were to try and do that you would essentially be labeled as a misogynist pig that thinks he can control his partners life. Some would even call it abusive.

You could say that if she was in a legitimate dance class, like many women who also happen to be in relationships, that you would be a normal fucking human being and accept it.

You could say that even if you did have some sort of insecurities about her being in a dance class, that you would again be a normal fucking human being and accept it.

I would just lose respect for any woman that had the nerve to say that to me. That's massively cunt like behavior. I mean, most men wouldn't even join a dancing class, you're trying to learn, trying to step out of the box, you're doing your thing... That threatens her. It probably makes her feel like she is boring, or doesn't have the same things to offer you that these other women who are taking part in the same sort of hobbies. She's probably thinking all those women will have a ton in common with you, shared interests, and she can't deal with it. The major problem here is that is incredibly child like behavior. It would never fly if it was reversed and it's fucking bullshit that she had the gull to say that.

I get it though, she's nice, sex is good, you get a long... Seriously though man, keep doing your thing. There are a million women who fit those criteria. Pick one that respects that you're learning to dance. Trust me, many would.