She's 49, and she ran into an old crush from High School last fall. She made a big deal out of friending him on FB and telling her life story. His third marriage is crumbling. I am not ready to face my fears about that yet.
I see that nobody has mentioned this to you that running into an old flame is a textbook reason a wayward starts acting like your wife is acting. I would encourage you to face that fear and face it NOW.. My suspicion is this "old crush" is the reason for the change in your wife...
Do your homework. I know you want to believe it is MLC. Wanting to believe something doesn't make it so.
Don't underestimate the power of an ex lover or crush coming into the picture after years apart. It happens all the time.