Dee Dee is smitten with her new beau, but the romance sours when she learns that he and Mona dated in high school. Although Mona gives her blessing to the union, she soon changes her mind.

When Dee Dee becomes frustrated with Neil because he does not seem interested in getting intimate, he divulges that he is celibate. Meanwhile, Mona is under pressure at work and takes up smoking again, but she is too embarrassed to admit it and tries to hide it from her family.

Mona fears a lonely Valentine's Day, but her tears may be for naught when two men from her (recent) past both ask her on dates. Also, Dee Dee is miffed that Neil would choose work over her. Meanwhile, Big Dee Dee is angry with her husband, who also chooses work over her.

When Mona has Spencer masquerade as her beau at a friend's wedding, Spencer realizes that he has romantic feelings for her, and has had them since college. Meanwhile, Dee Dee dumps her boyfriend when she learns he has matrimony on the mind.

Dee Dee invites everyone over to her parents' house for Christmas. The Bay Area experiences a heatwave, which leads to a brownout that nearly ruins dinner. Spencer angrily declines Mona's invitation, as the holiday brings up many issues about his absent father. Mona later offers to help Spencer track down his father. Phyllis brings her new boyfriend, a Santa Claus she met at the children's hospital, but both she and Charles object when the man refuses to keep his hands off of her. Neil calls Dee Dee and asks to come over and speak with her. She believes that he wants her back, and is stunned when he instead announces plans to marry. She tries to use the heat to her advantage in an attempt to win back Neil, while Mona urges her to just move on.

Mona and Dee Dee attend Neil's wedding, where their conversation with the already-nervous bride in the bathroom leads her to call off the wedding. Mona believes they should stay out of the situation to avoid causing further harm; but Dee Dee insists on taking in the devastated Neil when he shows up on her doorstep. Spencer regrets giving an overly generous tip to the stripper at Neil's bachelor party, and tries to get the woman to return it. Meanwhile, Big Dee Dee fears that she and Phyllis may actually have things in common after they run into each other at a funeral and discover that they both dated the deceased.

After throwing together a baby shower for Neil and Janet, Dee Dee becomes concerned by the fact that she is the only person in attendance who is not attached. She begins to question her life and decision to pursue her career so aggressively. Meanwhile, Mona worries that her lack of maternal instinct could have a negative effect on her relationship with Chase. She tries spending time with Drew, and receives some advice from Big Dee Dee.