Chace Crawford & Carrie Underwood: Why They Split

The singer and Gossip guy call it off. What went wrong?

Carrie Underwood‘s latest outlook on love? “You date to figure out what works and what doesn’t,” she says. “You’ve got to go through a lot of doesn’t before you find the one that does.”

Chace Crawford, apparently, turned out to be a doesn’t. The Oklahoma-born singer, 25, and the Texan Gossip Girl star, 22, who started stepping out together last fall, have called it quits. “We’ve parted ways,” Underwood confirms. “I actually haven’t spoken to him in over a month.”

Sources close to the two say Crawford wanted the romance to work. “Carrie is the one who broke Chace’s heart, not the other way around,” says an Underwood source. “He flew to visit her, went on tour with her—he did everything he could for this girl.” But in the end, according to a source close to Gossip Girl, Crawford “is the one who said, ‘Enough is enough.’ He was upset, but he also had to make the decision that it wasn’t meant to be anymore.” Underwood had always downplayed the relationship in the press: “I’m not serious with anybody,” she told PEOPLE in January. Another problem: Two sources say Underwood was still close to her former flame, Dallas Cowboys quarterback Tony Romo, 27, who now dates Jessica Simpson. “In any relationship, you need someone who is over their ex,” says the Gossip Girl source.

And what about all those women clamoring for Crawford’s attention? In between outings to Manhattan nightspots (and a Feb. 10 post-Grammys party in Beverly Hills) with Underwood, Crawford often hit the nightlife scene without her. But another friend says reports of Crawford’s flirting were exaggerated. “Girls would throw themselves at him, but he never did anything. He always smiled and was gracious, but that’s the Southerner in him.” For now, work keeps the two busy: Underwood is touring with Keith Urban, while Crawford is in New York City filming Gossip Girl, which returns to the CW on April 21. Says Underwood: “I’m good alone for a while. It’s been a while since I’ve just been single and free.”