I really need relationship advice right now, sex topic, only mature adults answer please?

Me and my girlfriend have been dating a year. We love eachother dearly for sure and plan to get married someday. Heres the issue. She won't give me head, period. She says that the thought grosses her out and it's not her thing. Not a huge deal to me. I have not pressured her and all but dropped the issue. Once in the year we've been dating she just for a second licked down there. Now I'm getting closer to popping the question but I wanted to know if she has ever given anyone else head. So i asked her and she said yes, a long time ago and she doesn't really remember it, just that it wasn't for very long and she was a bit tipsy. This has really hurt me since all of her past relationships have been short. Yet, some other guy got her to give him head. She was attracted to him enough and had feelings for him enough to give him oral yet she won't for me "the man she loves most". I'm trying to talk to her about it and she says it doesn't matter and to drop it. How do I address this? Am I wrong to be hurt by this knowledge of her giving another man head in the past when tipsy but will not give it to me? And what happen's now? What would you do if you were me? Please help, I have no one to talk to about this.