My Dad was the marrying type, though he and my Mom lasted 33 years (his 2nd marriage). He had four under his belt in his lifetime. He was the only one in his large family that ever divorced. When he and my Mom divorced though it was a mistake. They should have hashed it out, she could have (verbally) knocked some sense into him, but they didn't make that choice. It would have saved both of them many years of suffering.

Oh well, such is life. I hope your MIL will find happiness with #6.

BTW, I'm the only one of my siblings who has never been divorced.