HOLLYWOOD, Calif. — T.R. Knight is back on the market.

The former Grey's Anatomy star and his boyfriend, Mark Cornelsen, have split after nearly two years of dating, a source tells American Superstar.

"It was a friendly breakup," says an insider close to the pair. "The relationship had run it's course and it was time for new beginnings."

Knight, 36, and Cornelsen, 20, first met at a Matthew Sheperd Foundation gala in Los Angeles.

In June, Knight confirmed his plans to leave Grey's after months of rumors. The actor, who is currently appearing in the Tony-winning musical Parade at the Mark Taper Forum in L.A., revealed his desires for a baby last week on the Ellen DeGeneres Show.

"I don't know if it's going to end up working out," he said, "but that would be something I would like."