You assume their is no personal reward for her. I bring my wife to orgasm nearly every time we are intimate. Most of the time she has two, three or even four orgasms (one or two from oral/manual foreplay, and one or two from intercourse). The only times she doesn't have an orgasm is when she doesn't allow herself to be in the moment.
I am aware that for many women this is not the case, which I agree is not fair for them to be expected to routinely perform with no personal reward, provided the reason is because their partner is a selfish and inattentive lover. However, is she is has never had an orgasm and yet is unwilling to work at it with her partner, then I have no sympathy.
If I lost my ability to have an erection, I would still want to please my wife sexually because it is very gratifying for me to please her this way.

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