It could be an onset of dementia. My sister in law thinks it depression. But the pattern has been around in their relationship for many years, so I don't see it as much of anything new. My MIL was always the outspoken aggressive one and my FIL was more of a laid back 'accept the world as it is' kind of guy. This has never sat well with my MIL despite the fact that she has believed for religious reasons that she has to accept the authority of her husband. She's played the subservient role for years, despite her innate tendency to do otherwise, and I think it's coming out as resentment in her golden years. My FIL's failing health is the lance that pierced the pustule.

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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