John Mayer on Katy Perry split: "Coupling is a tricky thing" John Mayer has been known to talk candidly about his ex-girlfriends. Very candidly. Sexual napalm, anyone? But not this time around. It appears the singer-songwriter may have learned his lesson. When asked about his recent split from Katy Perry during Tuesday's appearance on "The Ellen DeGeneres Show," Mayer kept mum on details, but he did acknowledge the break-up, calling it "difficult." "Coupling is a tricky thing," he added. It was a very private relationship going in. It was a private relationship during. And it's a private relationship still and I can understand asking the question based on previous answers I've given," Mayer said. Those "answers" involved two of Mayer's famous ex-girlfriends, Jessica Simpson and Jennifer Aniston. In a 2010 interview with Playboy, Mayer spoke about dating Aniston: "I'll always be sorry that it didn't last. In some ways I wish I could be with her. But I can't change the fact that I need to be 32. The rebirth of John Mayer But it was his comments about Simpson that really got people talking: "That girl, for me, is a drug. And drugs aren't good for you if you do lots of them. Yeah, that girl is like crack cocaine to me...Sexually it was crazy. That's all I'll say. It was like napalm, sexual napalm. Mayer, now 35, apparently did some growing up. "I've finally learned how to put the wall between one thing and another, and I've been much happier since then," said Mayer, who started dating Perry last summer. They called it quits last month. Mayer's interview airs Tuesday on "The Ellen DeGeneres Show." He's due to hit the road this summer on his first tour since facing vocal cord issues.