I know of an instance of this in the family and it is only one perspective.
A male relative was married with kids. He was in the forces and was posted every couple of years. The wife did not want to work as her mother didn't work and was a sahm (both kids in school at this point), so it was setup that he would send her his salary every month and keep a couple of hundred pounds for himself. She refused to move with him when he was posted and wanted a house near her parents, which they brought. We thought this was understandable as she wanted stability and support but it did backfire spectacularly.
Despite meeting him when he was serving, she wouldn't support him at all in his career. Wasn't happy when he was away but when he came home he was pretty much frozen out. It was clear to us he really wasn't welcome or wanted. Inlaws ruled the house, dictated what would happen and he was pretty much ignored. The justifications were because he was away they had to take over. I think resentment built up because he didn't feel included at home, kids didn't know him, wife refused to work and he was living on a very small amount paying for a home he didn't feel welcome in. Recipe for disaster really.
So he stayed away more and more. Wife wasn't happy, not really sure why because that's what she seemed to want. She sent a letter threatening divorce if he didn't give up his career whilst he was away on operational duty. He was very angry as he was risking his life and said he didn't need that whilst he was doing everything they asked of him (bought the house, sent the money, didn't rock the boat with inlaws). I think a switch flicked at that point from what he said.
Anyway long story short, he ended up meeting someone and within 3 weeks of meeting the new woman, he had left his wife and agreed to the wife's divorce threat. Ex wife went ballistic as he regained financial control of his money, started divorce proceedings and a judge ordered her to work. Inlaws poured poison into the kids ears about their dad. A lot of anger. Thankfully, kids didn't listen to negativity and insisted on seeing their dad. They started to have a better relationship from that point onwards, just him and them spending time together consistently. He never missed a CM payment and gave her the house.
25 years later, he's still with the woman he met, happily married with kids. His relationship with his children from the first marriage actually became stronger and is really good now. All the kids get on and the younger kids love their older siblings.The older ones spoil the younger ones, it's lovely to see! Ex wife remarried and its all settled down. They still bad mouth him, especially his ex MIL as he's an easy punchbag, but never acknowledge anything they did wrong.
I like the woman he met, she's much more balanced, stands on her own two feet professionally and actually supports him which is nice to see (he went on to do a degree which we never thought he would). Ex wife said to us he shouldn't do a degree because it was selfish. Looking back I actually think she was financially abusing him. Would threaten suicide to get her way and MIL was the same, pretty toxic.
I suppose his affair would be classed as an exit affair but they're still together and happy. I think what happened actually saved his relationship with his kids and got him out of a very toxic situation.
This may not be the scenario the OP was thinking about, but just wanted to say it's not all black and white. Some marriages are just toxic, even with kids involved, and people are better off apart. How they end can be messy and traumatic, but people are human.