First, What type of stupid question is who’s fault is divorce?
In most cases, two people came to a conclusion that they can’t live together, and ZE HU. Why is there a need in society to assign blame?
Secondly, my advice for couples who are thinking about divorce is to go to a therapist, not a rav. Speak to most divorced couples and they will most likely tell you that speaking to a rav just made it worse.