Hot n Cold: Katy Perry and John Mayer Split … Again

John Mayer and Katy Perry's last appearance together was at the Hollywood Stands Up To Cancer event on Jan. 28. …

The days of Katy Perry calling John Mayer "darling" are over.

The pair's "Hot n Cold" romance, which began in June 2012, has chilled once again. According to multiple reports, the "Roar" songstress and the "Paper Doll" singer have ended their romance. E! News says the split, initiated by Perry, took place "within the last few days" after she returned from Europe. Us Weekly reports they had been fighting a lot recently and one issue was her upcoming Prismatic Tour, which has her stressed and will make it difficult for them to see each other.

Neither of the "Who You Love" crooners is speaking out about the split. A spokesperson for Mayer, 36, tells "The Insider With Yahoo," "No comment"; a rep for Perry, 29, says, "As always, we don’t comment on her personal life.”

The high-profile pair was one of the music world's hottest couples. However, despite their open affection for one another, their relationship wasn't without difficulty.

They quietly started dating in the summer of 2012, but split by Labor Day. The following month they reunited and, during that second shot at love, attended public events together, including President Obama's inauguration and the 2013 Grammys. However, by March it was over again.

During an appearance on "The Ellen DeGeneres Show" soon after, Mayer said, "Coupling is a tricky thing."

Perry, who ended a brief marriage to Russell Brand prior to dating Mayer, said that split was related to some issues she needed to work out, which she was able to do and they reunited by June.

"I realized I could lose the person I loved and I had to deal with some things, issues I think a lot of women have," she told Elle U.K. "You can be strong in one aspect of your life but submissive in another. In relationships, it was hard for me to speak up and set boundaries. I think a lot of that was to do with the fear of loss."

With their problems sorted, they started spending time together again and really kicked things up. They released a musical collaboration, "Who You Love," in September, and did a joint interview to perform their love song. In December, she was a surprise guest as his concert in Brooklyn and they performed the duet live.

Mayer said the idea behind the song was best described as, "I love you based on the fact that I've tried to run and I'm not running and I give up."
This year, they've stepped out together for a Grammy party and the Grammy salute to the Beatles concert. They also attended a Hollywood Stands Up to Cancer event on Jan. 28, which was their last red carpet appearance together.

On Valentine's Day, Perry flashed a ring on that finger at Sunset Towers in Los Angeles, sparking rumors that they were engaged. But Perry soon jetted off solo to Europe, where she had a difficult time at Milan Fashion Week. When she returned to the States on Friday, she attended a Miley Cyrus concert at the Staples Center in Los Angeles and shared a smooch with the twerk-loving performer during the show.

With their relationship kaput, it will be the end for Perry's many public proclamations about her beau. The singer, who called him "darling," told Billboard he was a "genius" and she planned to give his brain to science after he died so the world could "understand how all these sparks work.'" She's also called him "incredible," "inspiring," and said she was dating her celebrity crush.

Only time will tell if this is really the end for the pair.