Cher and Gregg Allman.
Cher divorced Sonny Bono acrimoniously in 1974. A year later, she rather impulsively married Allman Brothers keyboard player Gregg Allman.
However, she discovered that Allman was strung out on heroin and practically incoherent most of the time and nine days later filed for separation.
Allman managed to woo her back a few weeks later but Cher was completely stressed out by living with Allman. Then when she tried to reunite with Sonny Bono for a new Sonny and Cher TV show in 1976, it was Allman who filed for divorce. Except he learned she was pregnant with his child.
They stayed together for another acrimonious year and then split for good. Cher couldn’t stand the idea that Allman might fall off the wagon.