ABBA
In early 1979, Agnetha and Bjorn divorced. In early 1981, Frida and Benny also got divorced. This led to many sadder and more mature songs over the next few years.  By 1981, ABBA's popularity was declining. Their last album, "The Visitors" a not a big success like previous albums.  "The Day Before You Came" was the last song ABBA ever recorded together, while "Under Attack" was the last song ever released, both in 1982.  ABBA broke up shortly before 1983 and all members continued on their independent music careers, just like before they had met.