Doug, Carrie, Deacon (Victor Williams) and Kelly (Merrin Dungey) attend a wedding of a man Carrie had sex with once, but Doug did not know until right before the wedding and he does not tell Carrie he knows.

On Valentine's Day, Arthur attends a party at his senior center and meets a woman Mary (Jerry Stiller's real-life wife Anne Meara) and the two begin a love affair. Carrie is waiting for Doug at restaurant but Doug is stuck at Spence's birthday party, but when Spence arrives, he and his mother (Grace Zabriskie) get into a fight and Doug, Deacon and Richie are stuck at his home with Spence's mother; while waiting for Doug, Carrie meets a "schmuck" (Shaun Weiss) at the restaurant and transforms him to be more charming.

After Carrie tells Doug that it's okay for him to find other women attractive, he asks her to tell him which men she finds attractive. Among others, she says she finds Deacon good looking, which causes Doug to become jealous. Doug complains about it to Deacon, who brags about it to his wife, Kelly. Deacon's paintball birthday party turns into a jealous war.

A hurricane destroys the fence separating the backyards of the Heffernans and the Sackskys (Bryan Cranston and Dee Dee Rescher). When Carrie rejects their idea of a combined backyard by reinstalling the fence, the Sackskys retaliate by installing an above ground pool.

Doug gets a night job working as limo driver and tells Arthur that because the contractor they were using is now too expensive with Carrie being pregnant, he would finish the downstairs bathroom himself. However, the responsibility of working two jobs and Arthur constantly bothering him to finish his bathroom prove too much for Doug, in which he finally collapses at one of Carrie's appointments. In the end, she loses the baby.

When Carrie and Arthur's constant fighting begins to irritate Doug, Arthur is taken to a therapist (William Hurt) to discuss why he has to yell and act up all the time. It is revealed that Arthur's problems stem from his childhood, by being horribly treated by his own father (Ben Stiller). With Arthur cured, Doug and Carrie realize that Arthur wasn’t the only one with issues, leading them to take turns dealing with problems of their own.

When their bed breaks, Doug and Carrie order a new one but it won't arrive for several days. In the meantime they get two single beds and realize they sleep better that way. They eventually discover that being apart works, they see separate movies, eat at separate restaurants and even joke about taking separate vacations. But in the end they find they want to be together.

Carrie learns that Doug has fantasies about other women and makes a specific list of women that she approves of for him to dream about.

When Doug and Carrie start training with their neighbor Lou Ferrigno so Carrie can lose a few pounds, Doug works out a deal with Lou to just laze around during exercise time.

Doug realizes Deacon's new best friend is just a black version of himself. Meanwhile, Carrie has a problem at her nail salon: her mani/pedicurist "cancels" her.

Carrie goes away with Arthur to visit her mother's grave, and finds out she's not who she thinks she is. Doug and Ray Barone (Ray Romano) spend the weekend trying to pick up girls, attempting to outdo each other in a nightclub.

It's Doug's 40th birthday and Carrie begins to try to make Doug realize that he should start wanting to do more with his life. So Doug decides he wants to ride a roller coaster that he was too afraid to ride when he was younger. During this time, Arthur devises a plan to dodge long park lines.

Carrie is finally fed up with Arthur, so she decides to put him in a retirement home. Doug, of course, is excited but after a touching story told by Arthur, Doug tries to decide whether or not Arthur should go. Meanwhile, it's Danny and Spence's two-year anniversary living together and Spence reminds Danny on the bet they had on Spence getting the bigger room, but Danny is willing to fight him over it.