Wasn't very impressed by the show, myself...
** Spoiler Alert **
First, they only discussed sexually open marriage, not romantically, or at least that was my impression. I guess there was the part where the boyfriend tried to bring her flowers when she was in the hospital, to be met with complete rejection by the husband, whom we later find out is only going along with the open marriage thing because he doesn't want to lose his wife. So because of that lack of real honesty and openness, he is rather miserable with the whole situation.
Meanwhile we have one of the other doctors who's been having an affair and brings up the subject of this patient in an open marriage, testing the waters to see whether she would go for it. She already suspected his infidelity, and that all but confirmed it. She agrees to go along with it, putting up the usual restrictions ("Only on Thursdays and you come home by midnight"), only to pull the plug because she can't deal with it.
What also bothered me about the episode was that at the beginning, the doctors says "open marriages never work, it always ends up with one of the spouses being miserable" and then giving us a glimmer that it's possible, only to have the rug pulled out from under us when we learn that the husband does not truly support the idea.
I think this would be such an awesome idea for a Degrassi episode, though! I like to believe THEY would get it right