Putting a loved one at risk of a life altering std is abuse.
Not allowing them to consent to being in a non Monogamous relationship is abuse.
Gaslighting and lying to their face every day is abuse.
Cheating can cause a form of PTSD (pisd) in the betrayed. It is horrific to watch the weight loss, the repetition needed to process, the gaslighting and trickle truth. The lack of belief in self, fear to trust. The trip to the std clinic to make sure they don’t have hiv or another nasty std or hpv. That they haven’t maybe passed something onto a breast fed baby or toddler or their newborn.
Affairs aren’t sexy or cool - they are cheap. And they are abusive.
Lundy Bancroft covers men who cheat in several places in his book ‘why does he do that’. Some people cheat to punish their spouses. Others due to entitlement. Some because they have poor boundaries. But for all it’s a choice made after many micro decisions. And they hide it because they know it’s wrong.