The series revolves around three different relationships that are tightly intertwined in one family, as it follows a couple, Maddie and Ben, who had been dating for nine years and are happy just living together despite not taking the next step, marriage.
Joel and Ben accompany Casey on a road trip to Vermont to help him move his stuff out of storage. Ben looks at the trip as an opportunity to bond with Casey; but Joel sees the road trip as his annual chance to go off -- way off - of his salt-free diet. Meanwhile, the Putney women organize Mia's baby shower, and Casey's hard-to-please mother, the earthy but rather quirky Ariel, comes for a visit. Mia goes out of her way to be accepted by her future mother-in-law, but things get heated between Vicky and Ariel when both want their grandchild to call them "Nana."
Mia and Casey are excited when Maddie gets them a meeting with one of the top wedding planners in the city -- the charming but very expensive Lorraine Ashley. But the too-good-to-be-true arrangement turns awkward when it looks like Lorraine is trying to upstage the couple's pending nuptials. Meanwhile, Ben realizes that he has been with Maddie for so long that his "flirting muscle" has gone soft.
This Thanksgiving, everyone but Vicky is relieved when her oven breaks down. For once, the rest of the family can enjoy a normal Thanksgiving dinner and won't have to endure one of her unsavory concoctions -- such as maple syrup turkey stuffed with shrimp and raisins. And while spending the holiday at Maddie's and Ben's apartment, Mia accidentally finds her late grandmother's presumably stolen ring hidden in their linen closet... Now the unmarried couple has some explaining to do.
Maddie and Mia agree that they are not looking forward to the annual tradition of spending Christmas with everyone at the family lake house, so Mia and Casey use the pregnancy as their excuse and Maddie comes up with her own tall tale.
When Mia accuses Ben of ripping her favorite pair of jeans, she drags him to the store, where he has to break the tough news to Mia... it's time for pregnancy pants. Meanwhile Joel decides to get himself into shape after he finds out he's ranked last in Vicky and her girlfriends' fantasy husband draft website, and Maddie goes to extreme lengths to impress Casey with her high regard for the U.S. Postal Service.
After parents-to-be Mia and Casey adopt a cat, the pediatrician tells them they shouldn't have a stray animal around the baby. Maddie and Ben enter into a spirited competition with Vicky and Joel, all under the impression that if one of them takes in Mr. Meow-gi, then Mia and Casey will name that couple as the baby's guardian.
Casey has big plans for his first Valentine's Day with Mia. But Ben and Joel tell him that their rule is to never buy expensive Valentine's Day gifts for their ladies because doing so would set a costly precedent. Casey goes ahead with his plans anyway, and Ben realizes that he too wants to show Maddie how he feels. When Joel finds out, he decides to compete with them no matter the cost - and gets singer/pianist Michael Feinstein to perform.
The job interview-bound Casey, unaware that bad luck always follows the wearer of a particular leather jacket, borrows it without telling anyone. Everyone recalls their own bad experience while wearing the jacket, including Ben, who accidentally dropped a blanket on New York Yankee outfielder Nick Swisher when he was trying to catch a fly ball.
Ben hopes to get his name inscribed on a shamrock at his favorite bar, but it looks like he will strike out in his efforts when he learns the establishment's owner is New York Yankee Nick Swisher (appearing as himself), with whom Ben has a bad history. Meanwhile, Mia and Maddie use a secret language to convey their apprehension about attending a charity event with Vicky.
Maddie gets a feeling that the story Mia tells about how she and Casey met is not true; Vicky and Joel have Mia and Casey's engagement party at the country club and use it to promote Joel's campaign to be the club's treasurer
While in labor, Mia and Casey decide that they should be married before baby Charlie comes into the world. The rush is on to make the wedding happen, as Casey and Ben dash to City Hall for the marriage license; Maddie puts herself in charge of finding an authorized person to perform the ceremony; and Vicky and Joel hurry to the hospital's gift shop to find the "something old, something new, something borrowed, something blue" items.