If in the Twilight saga it's Edward Cullen who drains the life out of Bella Swan, in real life, it is the other way around. Kristen Stewart has reportedly "torn" Robert Pattinson's heart apart, according to entertainment sources.

The on and off sweethearts are said to have gone their separate ways again after a recent argument that resurrected all of the issues since Stewart's momentary indiscretion with movie director Rupert Sanders in July 2012.

"All this stuff came up," a close associate of Pattinson disclosed to Us Weekly.

The relationship apparently became rocky again when the 27-year-old Pattinson decided to snub the birthday celebration prepared for him by the 23-year-old Stewart.

"Kristen totally went out of her way to make Rob's birthday super special," one of the actress's friend told the Hollywood Life blog on Friday.

"She invited friends over to go swimming and just hang out for the late afternoon and evening. At the last minute, Rob said he didn't want to make his birthday a big deal and said he was just going to hang with the guys. Well, obviously this completely pissed off Kristen."

On the actor's side, he also had some issues brought up against Stewart, added the source. Aside from arguing about the cheating, he also complained about Stewart being selfish and how he's had to put up with her moods ever since.

Sources say that while the scar left by KStew's indiscretion has been difficult for Pattinson to take, it is the piling up of other unresolved issues that caused their most recent clash.

Observers, though, are still not discounting the fact that the couple might reconcile again. Because after initial stories on KStew's indiscretion last year, they did get back together even though Pattinson was "so torn."

Immediately after the news hit the headlines, Stewart publicly apologized to her boyfriend.

"This momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect, Rob," she said that time. "I love him, I love him, I'm so sorry."