I just read a post called “Adultery – Do not seek rationalisation” by MarriageRecoveryBlog. It’s well worth reading.
There can be a rational answer to the question. But, it will be a heartbreaking, disappointing answer that says the cheater is psychologically unfit and needs to grow up. The answer, in my case, is I cheated because I was selfish, self-centered, never satisfied, lacking compassion, lacking empathy, entitled, and nursing self-pity. I suspect most cheaters will have similar reasons for cheating.
If they suggest, in any way, that they cheated because of something the victim did or did not do, that’s unacceptable. Love is not transactional, love does not demand perfection from the object of desire, and above all love cares deeply about the spouse’s well-being. If such love exists, there can be no way to respond to perceived needs by cheating, by hurting their spouse.
“Why” is a big question. Just be prepared for a big answer: your cheating spouse valued himself more than he valued you. Any other answer from the cheating spouse would be a lie, victim-blaming, or manipulation.
Can that change, for the better? Yes, it can, but only with long-term re-prioritization and practicing empathy, compassion, selflessness, and real love.