Actually, the actor who played Ali (I believe) ended up killing someone in some sort of a sordid homosexual love crime.  He was thrown in prison, where he later hanged himself.

You may also be thinking of Fassbinder's later boyfriend, Armin Meier, who was jilted by Fassbinder and subsequently committed suicide.  The film 'In a Year of 13 Moons' was Fassbinder's "existential" way of dealing with his grief and guilt after that incident.