Recently, I told my girlfriend of my fantasy of her performing oral sex on me and swallowing my sperm. She said that would be "gross," and has never brought me to climax during oral sex because she does not want me to come in her mouth. I perform oral sex for her, and I enjoy having her sexual fluids on my face and tasting them but she will still not accept my sperm in her mouth.
I feel like she does not want to accept a part of me into her body -- that she does not have the fullest desire to please me. When I first asked her to do it, I expected her to want to pleasure me, to have desire for my penis. Now, I feel like she thinks my body is not desirable.
My question is: what must I do or say to make her change her mind, to make her understand how much I wish she'd do this?