I read it as either “he made some mistake that many people would consider unforgivable, but don’t judge a human by their worst day. We worked through it and overcame because he’s a good person at heart and I love him.”
He knew he was an A+ for letting her have more love at the end with the throuple. That’s class. That’s love. Bear with the swoosh for 1.5 years so your wife of 42 is happy. God he must be crushed right now.
I read it as rolling with her own joke and lightening the load on the B+ rating (obviously also expressed as a loving ribbing given the context around it)