John on Jen: "I Don't Waste People's Time"

John Mayer's been candid with the press before...But on August 16, the crooner opened to OK! about his breakup with Jennifer Aniston and the details of what went wrong.

"I ended a relationship to be alone because I don't want to waste somebody's time if something's not right," John told OK! exclusively. "I don't waste people's time."

Indeed, as OK! previously reported, Jen had been hoping for a wedding and the actress was dreaming about planning their "I do's," but it all proved to be too much, too soon for the notorious ladies' man, who ended things abruptly.

"John was getting cold feet about being in a serious, monogamous relationship," a friend of the singer, whose exes include Jennifer Love Hewitt, Jessica Simpson and Friday Night Lights actress Minka Kelly, reveals to OK!. "When he first started going out with Jen, he was enamored with her. She was everything he wanted in a girl: smart, funny and beautiful. But, to be quite honest, he got bored. He thought he could be faithful and that she'd hold his interest."

And, the pal adds, seeing magazine covers touting their upcoming wedding and baby plans got to be a bit too much for John. "He felt those things for a certain amount of time, but old habits die hard," explains the friend. "He doesn't want to settle down quite yet."

For the entire story on John and Jen's breakup, pick up the new OK!-- on newsstands everywhere on Thursday!