You now have two options.
You can make it known to her that this displeases you, and you break up with her. You are going to get called names like "you're just like everyone else", and crap like that. You're going to go out with soemone who looks just s good if not better, who will let you hit it, and you're gonna enjoy it and learn alot.
OR
You can make out with her, get her really really horny, and start fingering her down there. If she stops you from that, then you do the above step. If she doesn'y stop you, continue until she orgasms. Then, take your shirt off, and take your pants off. She'll see (hopefully) that you have a stiffy. She will either grab it or do something to it, or she'll get grossed out, in which case you stop, put your pants and shirt back on, and leave without a word, and do the above step.
YOU'RE A MAN. IF YOU DON'T GET WHAT YOU WANT, TAKE WHAT YOU WANT.