As often happens in the music business the Everly Brothers had their ups and they had their downs. Trying to run a business, trying to maintain a sense of self, constantly pressured to keep popping out those songs, they all took their toll.
Things got to the point where they brothers would arrive at the venue separately, perform their gig, and leave without ever speaking to one another.
The long-feuding Everlys split on July 14, 1973, when Don showed up drunk for an Everly Brothers show at Knotts Berry Farm – billed as their last performance. Phil tried to carry on, but finally got so mad that he smashed his guitar and stormed off the stage, leaving Don to finish the show alone. They only saw each other in person once over the next 10 years — at their father’s 1975 funeral.
http://listeningroom.lohudblogs.com/2009/11/28/rocks-sibling-rivalries/They did reunite in 1983 onstage for two concerts at London’s Royal Albert Hall. The event is taped and released as Reunion Concert, an album and home video.
https://www.rockhall.com/inductees/the-everly-brothers/timeline/In 2003, Paul Simon, who counts the Everlys as his biggest influence, talked them into touring with Simon and Garfunkel. "It was hilarious that the four of us were doing this tour, given our collective histories of squabbling," Simon told Rolling Stone. "Don and Phil hadn't seen each other in about three years. They met in the parking lot before the first gig." When the tour ended, the brothers went their separate ways and haven't performed together since.
http://www.rollingstone.com/music/pictures/the-11-greatest-rock-feuds-of-all-time-20110101/the-everly-brothers-rocks-first-sibling-rivalry-0009795My point in all of this isn't to criticize - it's only to bring more context to the lives of the guys who sang such sweet harmonies. It looks like they were able to reconcile their differences even though they went their separate ways. My musical appetites outgrew their music but my brother and I often played their tunes around the campfire and for the kids.
RIP Phil Everly