(Answered by John Eustace)
Its a common story. They started as a band of equals, with all of them being monsters at their instruments. Stewart Copeland was a fierce virtuoso on a drum kit, able to play complex and incredibly fast rhythms, Andy Summers was a virtuoso guitarist with a strong avant garde lean, and Sting was a superb bassist and singer with a distinctive voice, as well as being incredibly great looking.
I’ve heard several bootleg recordings from their early tours, and since they didn’t have a lot of songs, they would often play extended jams during the songs they had. During those jams, you can often hear grooves emerge that later became the riffs and foundations for new songs that would appear on later albums. It would be easy for a band member to assume that many of the songs were written by the entire band, at least in part. As time went on, Sting emerged as the primary songwriter, simply because his songs, and his lyrics were superior to the others.
This really bothered Copeland, who had developed an interesting new wave compositional style of his own. and he was frustrated that he couldn’t get his songs on the albums. Sting eventually allowed Copeland and Summers to have one one song each on the Synchronicity album. Copeland delivered the terrific song Miss Gradenko, while Summers decided to offend everybody with his punk anthem Mother, everybody’s least favorite song on the album (although I’ve always loved it). As interesting as both songs were, they sounded out of place on Sting’s carefully crafted masterpiece. Having to beg for space on the album, only to find that Sting was right anyway, had to have stung. Copeland started developing his own solo career under the name Klark Kent, where he could put out excellent new wave songs in his signature style without having to compete with, or get permission from, Sting.
Along the way, Sting’s ego had become huge, and there was talk of Copeland’s ego getting pretty big as well. To this day, Sting has a reputation of being extremely arrogant.
So they started off as a business arrangement, and as they got popular, their egos grew, clashed, and the band ended. Not the first story like that, nor the last.
Every Moment Has A Song 