@Apricot10 So much of what you say is so familiar to me. I think I may have posted already at the start (I lose track sadly as there are so many similar posts
) but my husband of 13 years (together 18, known each other since teenagers) had an affair with a 27 year old (he was about to turn 40). It was hell...absolute hell, but it was 2 years ago now and it does get better. I still feel incredibly sad when I think too much about it all as we were best friends, never argued, were the couple everyone though would be together forever...
This resonated with me: Some men are simply opportunists. He's likely seen this girl, she's shown some interest, and all of a sudden he can think of a million reasons why his marriage isn't working. Judging by what the OP has said (she is totally awesome, by the way) my take is that it's highly likely he'll come crawling back. The day he hears she's got a BF he will cry himself to sleep.
I don't think my husband was unhappy, as he likely told the OW and everyone else. I think, as you say, he got a bit bored with the life he signed up to when we had kids/a mortgage/marriage and was shown some attention and a chance at a more 'exciting' life.
However, after 2 years he split with the OW because from what i can gather, she had little interest in playing step mum to 2 pre-teen kids and actually had an issue with how much of his time he spent with his children! Hilarious! Thankfully he is a good dad and has been reliable in seeing them regularly. he rented a house fairly quickly so that he could do his fair share.
He is now seeing someone else as far as I know (older this time, with children and complications of her own funnily enough) and I have been in another relationship for 5 months. We communicate regularly about the kids, we can have conversations and we even do some of the 'talks' and chastising of the kids together as a united front. It's taken two years to get to this point and a lot of tears and hard work from me but ultimately, we both love our children and want this to affect them as little as possible.
I think he has massive regrets, although he knows me better than to tell me so because it would be futile. He chased after something that wasn't real and lost what was. That's for him to live with.
Well done to you, your children sound lovely and are very lucky to have you in their corner. I hope in time their dad realises that he needs to grow up and be the dad they deserve too.