I was seeking divorce and separated from my 2nd husband. Our marriage was brief; 6 years total (including the time were living separately before our divorce was final). I left him due to the nearly 2 dozen affairs he had, and because he was using anabolic steroids, resulting in roid rage.
I got a phone call from a woman saying that I should back off, her boyfriend was taken. I informed her that her boyfriend was my husband.
I had begun seeing someone while we were separated and our divorce was not yet final. At that point, I didn’t consider it cheating as we were just waiting for the divorce to be final.
He managed to get the guy’s number and called him to say I had a husband and I was cheating.
Apparently, he could see other women before we separated but I wasn’t supposed to see any guys after our separation.
He moved on, got a new girlfriend, but before long, he was cheating on her, too.
I think the thrill of the hunt is what turned him into a serial cheater. Once he caught that prey, the thrill was gone. I doubt he’ll ever change, he found cheating to be thrilling and saw no reason to change.