Gay male friend grabbed my *** when we were dancing?

I told him not to do that again. He knows that some areas of my body are out of bounds. So why did he do it. He is totally gay and has a boyfriend. He also joked before about touching my bust but he knows that I wont let him. He always holds me and plays with my fingers and protects me from other men who want to har me. Like he owns me. He jokingly said that I am his woman. I enjoy the affection but he should know that our friendship is strictly platonic. Why do gay guys think they can grope you just because they are gay. I think I am the substitute for when his boyfriend is not there or he enjoys being male and having a female. What do you think. By the way, he wasnt always gay but has been for years.