"Zach being away and filming was not easy on them," a source told the celebrity news website. "Now he's going to be in New York with his new play ['The Glass Menagerie.'] They really loved each other, so it wasn't an easy split. It just ran its course. Zach has been out and about and he seems fine."
Quinto, 36, is best known for playing Mr. Spock in two Star Trek films. He also is a cast member of TV's "American Horror Story."
Groff, 28, is one of the stars of "Glee."