AceShowbiz -

John Mayer makes music from his heart. The 39-year-old crooner has revealed that his new song "Never on the Day You Leave" off his latest album "The Search for Everything" is so personal to him that it could literally make him cry when singing it. That's the reason why he has never performed it live.

"Where this song comes in was I was really, really sad, like the kind of sad...everyone's there once in their lives, hopefully only once," he told SiriusXM Radio's "The Highway". "I was sad about everything. And this song idea came to my mind, and it was like, 'Never on the Day You Leave'. I don't know where it came from, but I just thought, all at once it came out full-cloth, and the song was written in 20 minutes."

The Grammy-winning artist shared that the heartbreak song is about one of his exes. "There's a line in there that's so brutal because it's so true. 'She'll fight for you like hell, then force herself to like some other man,' " he explained. The singer has had a number of high-profile relationships over the years, including with Taylor Swift, Jessica Simpson, Jennifer Aniston and Katy Perry.

"Every time I sang that line, I would cry in the middle of that line. It took me days and days and days to be able to sing that line for the record and get through it without crying," John recalled. "I can't play the song live because I don't think I could make it through it. Like, I haven't played the song live, I don't think I can. I don't like to think about it."