When I read something like this, I always wonder if it isn't my own boyfriend writing in. :)
i like to give head, but I don't like to do it as much as he wants. I mean, he'd like it every night, right? How often do you want her to perform it? What is your idea of "very rarely"? She might think otherwise, you never know.
Make sure you're clean. Maybe shower right beforehand. That helps me! Be vocal. I like to do it more when I know he really enjoys it.
Give her pointers; maybe she doesn't think she's good at it?
I think this is very important: tell her that there's no pressure to "make" you ejaculate. If she thinks the pressure's off, then she won't feel obligated to go forever, and might enjoy it more. Of course you want to ejaculate, but you might have to go without a couple times so she understands that you're sincere about it.
Of course, tell her when you're about to come so she has options! Many girls don't like to be "surprised" by a mouthful of semen. Have you tasted your semen before? If not, why? You can't expect a girl to lap it up and be disgusted by it yourself. :)
try doing "69". Not my favorite thing, I like to concentrate on one thing at a time, but maybe you can start by 69 and then give each other head separately.
Watch porn together.
I hope this helps! Good luck.