Reminds me of a story my ex once told me about one of his patients. Her husband had left in a MLC. They divorced. Two years later he begged her to take him back, but it was too late, she had moved on.
He told me this story, remarking on how sad it was, about a year before my ex had an affair!
The chemicals of infatuation in the brain light up the same locations that cocaine does.
Interesting that your brother turned around in just two months. I’m guessing your xsil did NOT spend those two months clinging and pleading for him to come home, right?