Is it normal that she is so timid about sex?

I am currently having some issues with my girlfriend. I have come to the conclusion that our sex life is failing fast and its because I am more kinky than she is. She is just into the plain boring missionary style of sex. She seems so distant during as well. She won`t even swallow my cum either which makes me feel unwanted. The kinkiest thing she ever let me do to her was cum inside her ass, and even that was terrible because she was literally crying hysterically the whole time. And afterwards she just sat on the bed while staring at the wall while shaking a little bit. She is a very quiet and shy girl. She told me that when she was around 12 her step grandpa would masturbate in front of her on at least 5 different occasions. It was really awkward and hard for me to understand her thinking after she told me she let her step grandpa finger her. She said it went on for about 3 months almost every other day or so. She said that her grandpa would give her orgasms even when she tried not to. Should I just break up with her? She seems too far gone for help and I dont know what to do.