I'm in a similar situation, I like to give it but my B/F doesn't. I tried talking to him about it one time but he got embarrassed and defesive and it killed the mood. He told me he does it when he's in the 'mood'. We've been together for a year and so far he's been in the mood twice.
The thing is though, I've tried to put myself in his shoes and imagine what I'd feel like if he were pressuring me to give him head and I had some sort of aversion to it. I'd feel violated and probably kinda yucky about it. I'd figure if he didn't love me enough not to make me do that just for his pleasure then I didn't really want to be with him.
When I gave some thought to it like this, I dropped it completely. Now, if he decided to do it of his own accord I would consider it a wonderful surprise.