At what point are you giving up? If you're touching her, and she's pushing your hand away when it wanders near her intimate areas, but she
doesn't leave then don't give up. Stop what you're doing, verbally agree with her "we aren't having sex tonight" or "this is going fast, let's just enjoy eachothers company." Then go back to touching her, say she looks tense, give her a massage. Don't start on the same part of her body that you stopped on.
Escalate as far as you can, stop, restart a little further back, escalate as far as you can. Until she actually gets up and leaves, just think of it this way. "She's turned on, but is resisting me. She isn't resisting me, she's resisting her own clit."
Also don't go in with the idea that you have to do all the work. Take her hands and put them on you. As much as it turns you on to touch her, it does the same for her. Let your shirt ride up a bit, put her hand on your abs. Unbutton your pants a little bit, make it easy for her to slide her hand down further.
Be prepared for this to take 5 hours. It could take longer than that, but honestly if she's arousing you for that long, you're going to get physically painful blue balls if you don't orgasm. If you still haven't gotten some clothes off, or her hand on your dick at 3-5 hours, let her know about your blue balls. If she's not a bitch, she will "help" you out.
http://www.youtube.com/watch?v=vciWSoAlkgA Watch this video, it's two guys discussing last minute resistance that they experienced, and the ways they got past it. They cover all the stuff I did above, and more. There's 3 parts so don't miss out on the other ones, they are free to watch. One of the two guys isn't the best speaker, but just listen to the content, he says what he wants to say eventually.