As they often say, stereotypes don't just fall from the sky. The whole notion of "my wife changed as soon as we got married" is not the NORM, but it's certainly not unheard of.

For most of the men that I talk to, their stories of "my wife completely changed" usually involves marriage, cohabitation, years together, kids, stress, jobs... you know, all the normal life stuff that can really CHANGE a person. BUT, for some guys and gals, their partner absolutely changed on the day of the wedding. As soon as things got "real", the person they know and loved just shut down completely. That's when they realized,  "Oh, this person was not marriage material." This person thrives in uncertainty and chaos. These are the women that jump from bad boy to bad boy. These are the guys that run to prostitutes and alcohol. Their childhood baggage is such that seeing "normal" scares the crap out of them.