Twice since last April
We've been together 12 years and my wife currently has no libido. About once every month or two she'll decide that it's not fair to me to be completely celebate, so she'll give me oral until I'm hard and asking to put it in, and finish quickly, please.
Unfortunately, the knowledge that your partner isn't into it at all is not good for the erection or the climax, so I have to have a porn-inspired fantasy in my head to finish. If I can't come or I lose my erection, she takes it as sign that she's too fat & ugly (she is overweight, but can still turn me on a lot when she's turned on), or that I'm old and no longer functional (no problem functioning with porn though), so I have to do what I have to do to finish.