I knew both him and his wife. She always seemed a very nice person. They had 2 kids and she put on a few pounds in the process. He decided to start screwing a much younger coworker of his, leading to the 1st couple getting divorced, and the second married. I woulda had no real objection if it had all taken place in a different order.
Hell, I don’t care how your feelings change towards your SO. Just split up/divorce - then get on with whatever you want.