It's not because the effect is much stronger in men ...... Studies have shown that on average the longer than woman in an exclusive relationship with a man, the less she wants sex with him.
Women don't cheat as much as men (though reporting may not be accurate) for lots of reasons - including
- lack of opportunity due to being more likely to not work outside the home, only work overtime, not work away as much, be much more saddled with family and childcare and household responsibilities, carve out less personal time for hobbies and in general,
also they are less risk taking than men - risk taking is often aligned with testosterone,
less selfish due to nature (care for kids) and socialisation, less entitled - again, values/socialisation still produce very entitled males in our society,
there are thought to be more male sociopaths and psychopaths than females (psychopaths font have to be axe murderers, they can be "ordinary" - it's said they are over represented in the higher levels of business organisations,
women usually have more to lose of their marriage or partnership breaks up. They are often more dependent financially. They'll often (always pretty much) be the main carers to kids, so they'll be the ones stuck between earning and childcare,
we have more of a culture of men being judged less badly forgiven for inappropriate sexual behaviour and cheating in ltrs than women (as evidence by your post).that was always more about power structures ... And controlling myths about women, so men know they'll be more likely to not suffer consequences
etc etc etc.
Loads of reasons not to do with the desire to have sex outside the relationship; but that do impact who feels entitled to go ahead and do it, who is selfish enough to go ahead, who is more of a risk taker, who knows the consequences if caught will be worse for them, who thinks most about any kids in the relationship etc etc.
There is an element of men's sexuality/sex drive being more steady, non hormone dependent and dominant in average (there are obviously exceptions) but there are lots more factors involved.