Guys are not in favour of a girl who does martial arts? (I learned Muay Thai)?

I have been doing mixed martial arts for 8 years, and it is my lifestyle (Not like MMA they do on TV, it's actually decent self-defense). My boyfriend is perfectly fine with it, but some guys just want to have the opportunity to be the hero. Some guys don't like tough girls like us; they want soft and weak girlfriends to feel superior.