You're right, this male dominated wrench forum may be able to diagnose mechanical problems but relationship advice may not be our strong point. I'm sorry to hear of your pain and hope that it subsides in the near future.
I think you're probably right that family issues may be at the root of it. It's very hard to separate family issues from spousal relationships. If there were tensions between you and her family, unless she had the same tensions with her family, they could have easily come between you.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13