Michael Scott and Jan Levinson's relationship was always one of the more controversial points of The Office. From their casual on-again, off-again beginning to when they declared it official, there were always a few signs that there was more to it than met the eye. No proof was offered to support anyone's suspicions until Jim and Pam agreed to join the duo for a couple's dinner.
In Season 4, Episode 13, "Dinner Party," Michael tricked Jim and Pam into finally coming to his home for dinner. With no other choice but to accept his invitation, the duo prepared for an unusual night, but they had no idea how bizarre the evening would get. Upon arriving at Michael's home, the two noticed the first strange occurrence of the evening: Jan seemed to have taken over Michael's house.
Since losing her job at Dunder Mifflin, Jan had moved in with Michael, but anyone seeing the house would assume the opposite. The walls were decorated with abstract art featuring Jan's face, and she'd completely taken over two rooms. Jan's tour also revealed she'd turned one into an office, and the second room into a workspace, explaining the extravagance by claiming she couldn't create where she worked. Michael didn't actually indicate his displeasure with the arrangement, but his mannerisms showed he wasn't entirely comfortable with it either. The master bedroom was even more disturbing. Apart from a suspiciously placed video recorder, Jim and Pam noticed a bench that Michael said served as his bed. He'd given up his actual bed on account of Jan's "space issues."
Next, Michael showed off a tiny plasma TV and his collection of Dundies hidden away in a corner. His explanation for why they weren't more prominently displayed gave an insight into his living situation with Jan; she was restricting the number of personal possessions he could have in his home. Even more evidence of Jan ignoring Michael's needs was her choice of music for the night. Despite Michael's visible discomfort, she played songs by her ex-assistant, Hunter. The song lyrics alluded to some aspects of Jan and Hunter's complicated relationship.
Ironically, Jan's jealousy flared when she noticed Michael gave Pam his jacket. Right after, she started to pressure Michael into telling the group how he broke their sliding glass door. Although Jan's version involved Michael accidentally running into the door in pursuit of an ice cream truck, his disturbed demeanor indicated the glass door incident may not have been an accident as Jan suggested.
Similar passive-aggressive behavior ensued during the dinner party, with Michael even half-jokingly calling her the devil and Jan saying she hated her life. The night got even worse when Jan insinuated that Michael always got his way. The comment upset Michael, and he yelled about just how much he sacrificed for her, including going through several vasectomies and reversals at her behest. When he calmed down, Jan gaslighted him by saying she didn't want to bring a child into their "screwed-up" world but would since Michael wanted it.
All was calm for a while until they finally sat down to dinner, and the evening reached its disastrous peak. Jan took offense to how Michael chose to eat his food, calling it disgusting. Michael retaliated by fetching his old neon sign Jan disapproved of and hung it up in their dining area. Not to be outdone, Jan once again played Hunter's music, which unfortunately started a screaming match between the two.
Furious, Jan rushed toward Michael's plasma TV and smashed it with one of his Dundies. The turn of events quickly put an end to the evening, and their guests started to leave, only to be greeted by the police. Jan's attitude completely shifted when she saw them, and she transformed into a caring girlfriend. As such, there were no arrests made, and Michael spent the evening with Dwight.
For a comedy like The Office, this episode was uncharacteristically dark. Jan and Michael's relationship was incredibly emotionally abusive and maybe even physically abusive as well. Although the episode retained much of the series' trademark humor, its more mature undertones were shockingly apparent. The dinner party made it clear that as much as Michael and Jan may have loved each other, they weren't compatible partners. Michael's juvenile nature didn't mix well with Jan's no-nonsense sensibilities. As such, her frustration with him may have led her to actions she wouldn't ordinarily take. The secrecy of their relationship also allowed these to continue as no one actually knew what living with Jan was like.
Jan's actions were inexcusable. However, the episode's conclusion showed her attempting to mend Michael's trophy that she had broken when she smashed it against the TV, implying she cared about him at some level. Their relationship may not have been a clear-cut case of abuse. However, it may be a peek into the potential endgame of a dysfunctional relationship pursued against all odds.