Brace yourselves, Twihards: After four very eventful years together, Robert Pattinson** and Kristen Stewart are taking a much-needed break, a source close to Pattinson, 27, tells Us Weekly. Additional Pattinson insiders add that the British actor and Stewart, 23, have been "having problems" and "fighting a lot," with things coming to a head on Pattinson's 27th birthday May 13.

Still, the first source adds that the much-scrutinized romance could go either way, and that a reconciliation is certainly possible. Just one week before the bitter birthday argument that led to the current split, in fact, the twosome were happily affectionate at NYC's Cabin, where Pattinson met Stewart following her solo appearance at the Met Gala.**

Former child star Stewart met the British actor when they were cast opposite one another in 2008's Twilight, the first of five blockbuster films based on Stephenie Meyer's bestselling vampire book series. As the movie phenomenon exploded over the years, the twosome very, very slowly went public with their romance.

The relationship was put to the ultimate test last July, when Stewart was photographed making out in a public park with Rupert Sanders, her married Snow White and the Huntsman director, in shocking exclusive photos revealed by Us Weekly. Quickly after Us broke the story, Stewart made her most public display of affection ever in a public apology.

"I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected," she said July 25. "This momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect the most, Rob. I love him, I love him, I'm so sorry."

(Sanders and wife Liberty Ross, meanwhile, are already done: The British model, who shares two young kids with the director, filed divorce papers in January.)

The pair reconciled by fall 2012, and jointly promoted Breaking Dawn: Part 2 together. They even appeared to survive several months thousands of miles apart as Pattinson filmed The Rover in Australia in early 2013.

Reps could not be reached for comment.

This article originally appeared on Usmagazine.com: Kristen Stewart, Robert Pattinson Break Up - For Now