Is it normal me and this one girl like each other but she has a bf

well my friend and i like to hang out a lot and we both also like each other but she has a boyfriend and he gets jelouse when i hang out with her and we started to hold hands and stuff when no one was around and we had a lot of fun but she feels bad and doesnt know if she wants to keep doing this and me and her boyfriend are kinda friends but he is too over protective and controling of her and idk if we should still hold hands and stuff?and im a really nice guy but i like her a lot so i still want to hold hands and stuff