Why will Castle and Beckett be apart at the beginning of this season's Castle? — Whitney
ADAM: I hear the decision to pull back from the relationship is Beckett's -- she may even lie to keep Castle at a distance. But Stana Katic
believes Beckett's actions are carefully calculated. "She's making an
adult decision not to dive into something because she doesn't want to
screw it up," Katic says. " She's dated other guys, but he's the only
guy she's been in love with."
Source: TV Guide