Occasionally, even the sturdiest trust-based relationships encounter problems. For example, a person having an age-related crisis and cheating on their partner of many years with whom they have a kid.
That’s the exact thing that happened to today’s OP — his wife of 13 years cheated on him because she felt insecure about getting older. And now, the man doesn’t want to give her a second chance, even though she promised never to do it again.