Being obliged to have sex with someone you no longer love must be hell on women, too. Sex is not a mere bodily function to most women, but a lot of men - (certainly not all) - do see it that way.
I think sex without love is as ‘adulterous’ as anything else. Love is all that really condones it.
Imagine being verbally and/or physically abused all day long, then being expected to feel all warm and fuzzy in bed that night. Eewww.