I agree with nightangel. Communication and lubrication might be good for you both.
You're very lucky to have a partner who is so generous to go through all of that even if she is not really in the mood. A lot of women prefer oral to sex, that's nothing new. More women orgasm to oral than they do to sex.
If your wife is having an orgasm during oral, you could try having her wait. That might keep her more in the mood during sex. Then you could give her an orgasm after the sex if she doesn't orgasm during it.
I will have to agree with angel on the 45 minute thing too. Even five minutes of giving someone oral is a chore and a half for me. Maybe you do not realize just how lucky you are.

Sounds like your wife should be getting roses every night.