A source says the Ghost Whisperer costars' decision to split was mutual

Credit: Jen Lowery/Startraks

Jennifer Love Hewitt and Jamie Kennedy have split, but the Ghost Whisperer costars are saving the drama for the small screen.

A source close to the couple insists there was no infidelity or other smoking gun behind their breakup, and says it was a mutual decision by two people who remain friends.

“It wasn’t contentious,” the source tells PEOPLE. “It had kind of just run its course They just sort of looked at each other and said, ‘We like each other and we make each other laugh, but this isn’t for the long-term.’ “

Hectic schedules may have also contributed to the split. In addition to starring in and producing Ghost Whisperer, Hewitt is preparing for an upcoming Lifetime movie, and getting ready for a tour to promote her first book, The Day I Shot Cupid, due out March 23. In the book, the star – quite fittingly – offers advice on relationships, love and weathering, among other things, breakups.

“She’s working constantly, and Jamie’s working on the show and touring [with his stand-up comedy act],” says the source. “It just isn’t conducive to a relationship.”

Still, the source says the former couple’s on-set relationship remains drama free and professional.