We have spoken about it at great length. He has never minimised or made excuses for it. I know how much he regrets his actions and wishes he could go back and do things differently. The relationship wasn't a happy one and he took the cowards exit door. The knock on effect this has had on his relationship with his DC/the time he now has with them breaks his heart and he goes over and above to see them as much as he possibly can. He had extensive counselling to try and gain insight and make whatever changes he felt needed to be made.
In the 1.5 years we have been together he has never caused me so much as a single moment of worry or doubt. He is totally open and transparent. I trust him.
Am I a fool? I truly don't believe that life is as black and white as the MN mantra of "Once a cheat always a cheat" and I know from my own previous long term relationship that monogamy/fidelity can be a tricky path to navigate. I have done things in the past that I now bitterly regret and know I would never do again. Is it not possible that he has also matured and learned from his past as I have? Or is someone automatically a write off as a human being as soon as they have an affair? (I'm not defending affairs at all btw, just genuinely struggling to get my own thoughts/feelings on the subject figured out).
AIBU to believe that someone can fuck up in such a monumental way and learn from the experience and not inevitably do the same thing again?
This is all a bit jumbled, sorry. We're talking about moving in/marriage and I guess there is a tiny voice in the back of my head that says "He did it to his ex he might do it to you". But then again, someone who has never cheated before could also do it to me. You can never ever know what someone is going to do.
Any advice would be very welcome.