Speaking to the September issue of Elle UK magazine, Perry gives some insight into their breakup and their notably private relationship, while denying any romantic involvement with another high-profile male star.
Describing Mayer as "the love I thought I'd lost," Perry tells Elle UK that they split up because John "pulled away," and that served as a wake-up call for her to take a look at how she approached their romance.
"That was a big hello for me," she said. "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."
What kinds of things?
Perry, 28, said, "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."
Fear of loss would be understandable, considering her marriage to comedian Russell Brand ended in divorce a little more than a year later.
But Perry said she doesn't regret being involved with "challenging" guys.
"The men I have gone for are challenging, yes, but they're also wildly intelligent and poetic," she told Elle UK. "I'm not interested in taming anyone. I'm pretty wild myself."
Perry also took the opportunity to address rumors that she was romancing "Twilight" star Robert Pattinson. She said she reached out to Pattinson's ex, Kristen Stewart, to explain that there was nothing going on, but that the media was blowing everything out of proportion because she's a woman and he's a man.
"I sent her a text message saying, 'I know you've seen all this stuff but you know I would never disrespect you. I'm not that person. I'm just trying to be a friend to him but it is unfortunate that I do have a set of [boobs],'" Perry said.
As for her high-profile friendship with Rihanna, Perry said, "I love her, and every time I see her, I'm reminded of the light that she has."
"There's a lot of dark in this business," Perry added. "I know a lot of people out there with the most detrimental entourages. They are the root of their demise.
"It's really unfortunate but you can't save these people. My days of celebrity saving are over."
The magazine hits the stands Wednesday.