It is my belief that in marriages that involve women who don't like sex, this scenario isn't actually that far-fetched. She lays prone in the dark under the sheets for a couple minutes every once in a while. She may not have had much experience with sex, or simply disliked it enough that she really wasn't paying attention.
As a woman who actually enjoys sex and loves leaving the lights on, I can firmly attest to my husband's very male sexuality.
Firmly.
As for myself...if you look at pics of me as a kid you could assume I was a boy....