Of course, we humans do make mistakes, but some mistakes are truly inexcusable. The only circumstance I believe that gives a ground for divorce is adultery. Any other reason is invalid. For example, with irreconcilable differences, of course, there will be always differences between individuals, but that is no excuse for couples not to communicate and find the middle ground to work on things. This happens all too often when one has one vision of life/marriage and the other has a different vision. They can't claim that marriage won't go in the same direction because of that, but this is the very reason why sacrifices have to be made for the marriage to flourish and this is made possible by effective communication. Marriage is a sacred thing and people these days have destroyed the sanctity of marriage.
Yes, I do understand there other viewpoints besides mine. I am just showing that things can be reduced to lust and pride. It doesn't matter if the one who did the cheating has a story because people will have all kinds of reasons why they cheated. Nothing can justify the very act of cheating. Nothing good comes out of cheating. If two people are not happy in the relationship, one cannot just think, "Well, if she is not coming to me about her issues, that's her problem" and then go out and commit adultery. Who wants to be cheated on? No one. But unfortunately, it happens because of mainly lust.
This is precisely why people have to take the time to know someone before marrying that person. These days young people are rushing too quickly into a marriage. Also, a relationship may seem to be great, but then when the holy matrimony is performed, one or both individuals can settle down in the marriage and think it no longer requires work. Marriage requires work which includes changing of oneself for the better of life and the marriage per se.
Yes, people can change, but is the change for the better or the worse? Of course, it always has taken two people to make marriage, let alone any type of relationship (friendship, parent-child, courtship) to make it work. I like to say, "It takes two to tango."