Lou, what are your wife's UTI symptoms? Have you considered it might be VS? I've got that and the commonest age to get it is either puberty or menopause age. I got mine at age 12 with onset of periods.
Since she is post-menopausal and her hormones must have changed, there is a possibility of her having that, dependent on her symptoms.
Frequent UTI's and thrush are a side-effect of having VS.
I'd also like to tell you that at one point I was so physically ill with my VS that Andy and I were not able to ML for 9 months and even touch would cause huge inflammation to the point where he was afraid to even hug me in case that meant I wanted sex and then he'd be responsible for 'hurting' me.
Steroid about 5 times a day for a year or more was the only thing that put it under control.
Someone mentioned peeing after sex; well, I am unable to do that even now as the pain of urine passing over the vestibular tissue would be agonizing. I always wait 1 hour after sex before attempting to empty my bladder. I'm telling you this in the hope you inverstigate your wife's symptoms more as frequent UTI's can be a trigger factor for VS.
The other thing was, despite a lot of medical problems and pain I eventually managed a SL with Andy that was 3 to 4 times a week and it got to be very satisfying. Even on the times I experienced pain, I got to enjoy it and want it for the intimacy and closeness.
There are always ways round a situation, and if I can have a frequent SL with VS, then she should be able to have a SL with you, with UTI's.
