Clunky episode that tries to cover a lot of ground in Mary's romantic life.
Dan (Michael Tolan) returns. Dan was one of many single episode serious romances where the episode ends on a romantic high, but by the very next episode it's as if the guy never existed. Dan's first episode 'Room 223' was one of my favourite dating episodes, as the romance was well integrated into an otherwise good story, and there was lots of comedy besides.
Here, in the first part of the episode, Mary and Dan are awkwardly reunited. Awkward because Dan's new fiance is there too. Mary (and Rhoda) then agree to go to Dan's engagement party, which is a disaster due to Mary's presence. These parts are funny if a bit unbelievable.
In part two the engagement is off, and Dan and Mary are suddenly very serious. All of Mary's friends, family, and future in-laws, are apparently thrilled with the new arrangement. However Mary isn't sure she wants to lose what she has (independence, career, friends) for marriage just yet.
The second part with Mary's dilemma is believably articulated but overall this seems to be an eccentric episode.
The subplots (Ted tries to learn Swedish, Mary's fussy father keeps replacing the lock on her front door) seem a bit contrived.
They hand wave away why Mary and Dan stopped dating. I don't know though, maybe he heard about one of Mary's later boyfriends and backed off. He wouldn't have proposed had he seen what happened in intervening episodes 'Didn't You Used to Be... Wait... Don't Tell Me', and 'You Certainly Are a Big Boy'.