This is worth the link just for the title “On That List of Excuses for Not Having Sex Floating Around the Interweb” but the discussion is not at all frivolous, and the last paragraph is highly quotable:
[A] mismatch must be seen as just that. There’s no right amount of sex to have, so someone agreeing to it three times a month must be accepted as much as someone wanting it several times a day or never at all. It just is what it is. A mismatch is a problem for both the person not getting as much as they desire, and for the person denying the request, but it’s only a problem at all if people hold sex in their relationship as more important than care, respect, and love. If you care enough, you can become attuned to one another’s needs. It might mean not asking even if you’re feeling it, and it might, for some people so inclined, mean doing things you’re not really into right now. Love isn’t about giving everything of ourselves to another person, though, or solving all their problems ourselves, it’s about caring about their issues enough to be there while they find their own way.
In fact, it’s not even necessary for the schedules to be out of sync for there to be a problem, as Woody Allen noted back in the day:
[Alvy and Annie are seeing their therapists at the same time on a split screen]
Alvy Singer’s Therapist: How often do you sleep together?
Annie Hall’s Therapist: Do you have sex often?
Alvy Singer: [lamenting] Hardly ever. Maybe three times a week.
Annie Hall: [annoyed] Constantly. I’d say three times a week.
Never you mind why I’d remember this after, oh, thirty-seven years.
Oh, this is the list being referenced.