Jessica Simpson's New Man: John Mayer TUESDAY AUGUST 29, 2006 06:45PM EST TUESDAY AUGUST 29, 2006 08:00PM EST UPDATED Mayer and Simpson in 2005 Photo by: Lester Cohen / WireImage Jessica Simpson is embarking on a not-so-public affair with singer-songwriter John Mayer, PEOPLE has confirmed. "She's tiptoeing back into the dating world," a source tells PEOPLE. "It's the first stage. She's never been happier." Mayer, 28, began a co-headlining tour with Sheryl Crow on Aug. 24, and Simpson, 26, is expected to attend his concert in Jones Beach, N.Y., on Wednesday night. Simpson is currently in New York promoting her new album, A Public Affair, which was released Tuesday although a bruised vocal cord has quashed any planned performances. Similarly, Mayer had to cancel his Hartford, Conn., appearance with Crow on Saturday due to laryngitis, the Associated Press reported. The two singers have known each other for several years and last year both attended Clive Davis's pre-Grammys party in Beverly Hills. Although Simpson has been linked to Jared Leto and her Employee of the Month costar and Teen Choice Awards cohost Dane Cook, Simpson has not officially dated anyone since her November 2005 separation from Nick Lachey.