"I think when someone cheated on me, it was because they felt ignored and
unloved by me. Which was not the case. But you see what poor
communication can do."
He continued to lie to you.
You already know why people cheat. In some cases, like yours, the cheater will try to rationalize what they've done by placing blame on their partner. You can collect other reasons, but do mind your intuition on this matter.
It doesn't matter if they are ugly or beautiful, all types of people get cheated on. Keep this in mind, and it'll be easier for you to identify how he probably would have done this regardless of who he's with.
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I take it his actions lead you to look into sociopathy, which has us talking here.