The BBC

Last night we watched on DVD an episode of the BBC comedy hit The
Office. In it there was a scenario in which a secretary asks a
co-worker why he never comes around to talk to her anymore (b/c she
has a boyfriend). He pretends that nothing is wrong. Then she asks
him to go "wind up" an obnoxious co-worker as they often do, and he
acts like he doesn't know what she is talking about and tells her that
he is busy working and she should be too. This is a very direct
change from last season in which they were very chummy (the change has
occurred because she is engaged now).

He walks away, leaving to wonder whether something has happened, whether she can trust her instincts about their previous chumminess and the sudden change, and something has happened, why?