John Mayer loves Katy Perry -- and he also loves her massive new single, 'Roar.' The 'Paradise Valley' crooner couldn't stop bragging about his lady love's new song, as well as his collaboration with her, 'Who You Love.'

"In a way you get swallowed up by it, it's so big," Mayer told Billboard of Perry's hit 'Roar.' "Because it's such an incredibly big song that it doesn't need you to tell anybody, while you're eating lunch, [that] millions of people are going to be dancing on tables to that."

He continued, "I remember hearing it, going like, 'Wow what an interesting experience' to hear something that you identify as massive before it's massive. I thought it was a really sweet, unforgettable sort of experience to hear someone's work while they still have a very nascent relationship with it."

Don't you love how supportive these two are of one another's careers?

As for their duet, it's a pretty honest one, and Mayer revealed that both he and Perry wrote their own verses from the heart ... and if you pay attention to gossip columns, you can tell it's true!

"I started singing 'And my girl, she ain't the one I saw coming / Sometimes I don't know which way to go /And I tried to run before, but I'm not running anymore,'" Mayer said. "In 2013, modern-day times that's sweet. Because there's so many other things to occupy your time that you can do for yourself. That to say, I tried to be alone but I can't. This is sort of our generation." That certainly explains the ladies' man's fear of commitment when he and Perry were on-again-off-again, doesn't it? Sounds like she finally tamed him!

He further described the ode as "I love you based on the fact that I've tried to run and I'm not running and I give up." Sounds about right to us, right?

"I immediately thought about Katy and I was like, 'What a cool voice. What a cool artistic personality to have on.' It was a really fun opportunity for her to write like, her answer to that. So you get these two sides to this relationship that are brutally honest but no less universal."

Perry's answer, for the record? "My boy was not the one that I saw coming, some have said his heart's too hard to hold."

You love who you love -- and we love Perry and Mayer together!

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