Can't come when being given oral

[Torqueo]

The last few times my boyfriend and I have had sex, he's been giving me LOTS of oral, which is unlike him, but i'll live
Anway, when he did give me oral on the odd occasion, it was short and not really all that pleasing. But the last few nights he's been giving to me every chance he gets and veeery well.
But something's not right.
He does 'everything' right, he knows what movement I like, how hard to be, when to speed up and slow down, everything. But he can't seem to make me come. And as any guys here can imagine he thinks it's cos he's crap with oral. And any girls here will understand that I think it's my fault >_<
Before anyone says it, I know I can come because I can make myself do it, and I've done it whilst having sex with him.
So.
Any suggestions?