Clearly, it is the cding that causes the split, whether there were other problems or not. I mean if the cding didn't come out, there would be no ultimatum, at least not at that point, right? It is possible that the other issues may have had the effect that the wife was less accepting, of the cding. I mean if you are not getting along well, in general, it seems less likely she will try to be accepting.
Truly, once the parameters of the marriage are changed, we all have to re-evaluate, and make a call. This is influenced by love of one's partner, family, need to express oneself, etc. While one can understand where each other is coming from, it doesn't mean they will agree. That doesn't make either one of them a bad person. If the marriage does not work at that point, we could hope that "split" will be handled with as much grace and decorum as possible. Sadly, this doesn't always happen.