Adam thinks he's found true love when he bumps into Shelley -- literally. Meanwhile, Pete is driven up the wall by a very hormonal, pregnant Jenny. And Karen wants a nanny, but David won't hear of it.
Adam and Shelley want to cohabitate -- but in whose apartment? Pete goes beyond the call of duty to prepare for Jenny's birth. David takes it as a competition when his suitably yuppie co-worker boasts that his toddler is smarter than Josh.
After losing a promotion and gaining a new boss, Ellen, David starts having trouble performing in the bedroom, but his seeking help without admitting the problem is his leads to a series of misunderstandings. Pete and Jenny are terrified when her doctor informs them that they can have sex in two weeks -- and they're not sure they can. Shelley fears that her relationship with Adam might fall apart after they sign the lease to their new place.
Adam breaks up with Shelley after learning about a man from her past -- whom she happens to be married to -- and moves in with Pete and Jenny, while Shelley does likewise with David and Karen. Meanwhile, Karen falls hard for an author whose manuscript she has to edit -- after seeing nothing more than his photo on a dust jacket. And David is caught between a rock and a hard place when Ellen blackmails him.
Shelley worries Karen might feel compelled to cheat on David while she and Conrad are away on their book-signing tour. Karen mistakenly believes that Conrad has a thing for her, unaware that he's having an ""affair"" of his own. Meanwhile, Pete's annoying, intrusive parents, Stan and Stella, drop by unannounced, to Pete's and Jenny's chagrin.
When Shelley gets increasingly clumsy around Adam, including dropping a refrigerator on him, she wonders if she is subconsciously trying to sabotage their relationship.