For goodness sake, no one is saying that a marriage always collapses with equal responsibility to husband and wife.
I am saying a couple of things. Almost anything can be repaired, if the person who did it takes responsibility, asks mechila, and changes his or her ways, and takes it upon themselves to do differently every day in the future, and if their partner can rebuild their trust.
Also, even in cases where one partner’s wrongdoing would seem overtly to have more to do with the marriage breakdown, that wrongdoing itself can have had causes wholly or partly dependent on the actions of the other spouse.
I am not justifying the actions or the lack of taking responsibility if one partner has done something irreparable and not owned up. I am saying that two mature adults in most situations will likely recognize that they both did things to harm the marriage and they both need to learn from it.
Patri, people will say or blame their ex, in my view and experience, because they are trying to justify their feelings or actions, and maybe because they are not ready to take their part of the responsibility.
And, very importantly, sometimes divorced people feel compelled to point the finger at someone else because of the judgmental and critical nature of those observers who are talking about them as if they had the plague. I have B’H avoided that, and will IYH continue to do so.