Gossip Girl star Blake Lively and Leonardo DiCaprio have split up, their publicists had confirmed Tuesday. Is Ryan Reynolds a third party in the failed romance?

Reps for Lively, 24, and DiCaprio, 36, told Us Weekly, the decision to call the romance off was mutual and they "remain friends."

There has been no official statement yet as to the reason for their parting of ways, but rumor was quick to spread that Reynolds, with whom Lively starred in Green Lantern, is now dating the actress.

In an interview with Glamour magazine, Lively had said long ago that she does not dwell on the drama when a relationship ends.

"I have a strong sense of myself," she said. "That gives me a sense of security, you know? Every relationship you have, you're learning and growing and taking something from that."

"So for me, it's never been too dramatic of a thing when something ends."

In the meantime, E! Online has just reported that Lively may have already moved on with Reynolds, 35.

The Green Lantern leads were reportedly seen on an Amtrak train going from New York City to Boston where Ryan is currently filming R.I.P.D.

"Blake was late and almost missed the train," a passenger told E! Online, adding the two sat together in the first class cabin.

However, Reynolds and Lively were not conspicuous during a recent Radiohead concert, which they both attended. It is probably because Reynolds came to the concert with ex-wife Scarlett Johansson.

"Ryan and Scarlett came in together right before [the] show started and just watched, rocked out and left together . . . they just seemed like good friends," a source told Us.

First photographed together aboard Steven Spielberg's yacht in Monte Carlo on May 17 during the Cannes Film Festival, Lively and DiCaprio had since been spotted together in Venice, Italy, California, NYC and Australia.

Lively even flew from the U.S. to Sydney just to spend a weekend with her then boyfriend, who was filming The Great Gatsby in Australia late-August.