Lena and Martin were once madly in love. But, like many marriages, time and circumstance eventually took their toll, and they decide that everyone's lives would be better if they got a divorce. Facing a daunting real estate market, the couple decide not to sell their house and to "Bird Nest" instead. The 'on-duty' parent will live in the house while the 'off-duty' parent will live in the detached garage. As Lena begins to dip her toes into the dating waters, Martin begins to see his own culpability in his marriage falling apart.
Afraid that the answer could ruin his chances with Lena, Martin finds every way he can to avoid asking Lisa Apple if she is pregnant, while the potential pregnancy makes Lena more and more distant. At the same time, Lena worries Mason is changing himself to please his new girlfriend and finds parallels to her own relationship with Martin. Elsewhere, Maya tells Frank a pretend story about her "friend" who is dating someone new and pregnant to gauge what his honest reaction will be.
Lena decides to call Martin's bluff on selling the house but is surprised when he actually begins making necessary repairs to get the house ready to be sold. The realtor sends over a contractor to deal with the structural issues she discovered in the house. Meanwhile, upset that Mae is not enjoying her sophomore year of high school, Lena invites Emma-Rebecca, Mae's friend from camp, to visit; yet she seemingly brings a trail of bizarre and supernatural events along with her.
Lena and Martin's escalating battle for control of the house is put on hold when Milo announces he wants to go to a school for the gifted - to which they think he will not be accepted. Meanwhile, they both meet a contractor for the house, Vlad, but Lena undermines him and scares Vlad away. Things get uglier between Lena and Oliver after she introduces a new member to the family as payback for all the back-and-forth about the house. Elsewhere, Lena and Martin give conflicting advice to Mason on how to deal with his recent breakup.
Vlad, the new contractor for the house, arrives with his crew and Lena immediately begins to clash with him over his methods of repairing the house. Martin, on the other hand, feels that Lena should let them do what they were hired to do. After overhearing that she's too uptight, Lena calls up an old friend to help her let out her frustrations. Elsewhere, Martin takes Mason camping to help him get over his breakup with Hazel and to teach him how to be a man, only to learn from him that it is okay to express his emotions.
Lena tries to support Maya in any way she can with her pregnancy, only to get accused of being too controlling and taking over. Meanwhile, after Martin reads Mae's diary, he suspects that she is romantically involved with her teacher and panics. Elsewhere, Arthur and Camille volunteer to temporarily take in Arthur's teenage nephew to help his overworked sister .
Vlad announces that construction on the house is almost finished, even though Lena still thinks there's more work to be done. Later, he asks Lena to help him on another project with a client more difficult than she is. Meanwhile, Martin begins dating Paige, a divorcee who works in his building and doesn't understand the arrangement he has with Lena. Elsewhere, Camille tries to be a good influence on Arthur's nephew and is delighted by their relationship, but is later judged by her parenting style.
After Lena and Vlad's unexpected kiss, things get more complicated as they begin their new work partnership while working with a new client. Elsewhere, Martin goes to Paige's house for more privacy and gets a glimpse into what a more typical divorced home life is, causing him to become uneasy. Back at home, Mason and Mae go head-to-head after Mae finds out that Mason has a crush on a pretentious girl at school.
Frazzled by her intimate dream about Martin, Lena accidentally injures her tooth and reluctantly goes to the dentist; Martin escorts Lena to Mae's parent-teacher conference after she inadvertently gets high; Maya asks a familiar face out on a date.
A concerned Lena tries to figure out if Mae is romantically involved with her new best friend, China. To make matters worse, Mae asks if China can sleep over, which makes Lena uncomfortable and forces her to confront her own issues with intimacy. Meanwhile, Martin worries about Mason's relationship with his new girlfriend, Bronwyn, and gives him advice to help avoid another heartbreak.
Camille urges Lena to become more active on social media to get her business off the ground. Once on Instagram, Lena messages design advice to Tamryn, a famous social media influencer who ends up hiring Lena to design her child's play room. Meanwhile, Camille has doubts about Tamryn's intentions and warns Lena that the friendship is one-sided. Elsewhere, Martin takes over for Lena as Milo's room parent and investigates why Milo is feared by his classmates.
After a doctor's visit, Arthur learns he's under high stress due to Valentine's Day approaching. To de-stress, Arthur suggests his concerns to Camille and asks if they can take a break from the holiday which causes them to fight. He shows up at Lena and Martin's house, where they help by taking him in. Meanwhile, Maya and Camille express disapproval when Lena decides she wants to cook a platonic Valentine's Day dinner for Martin at home. Elsewhere, Mason organizes a Valentine's Day flash mob for his girlfriend.
Lena confirms that she has feelings for Martin but is confused when his response is not what she expects. To escape the situation, Lena joins Camille and Maya on a road trip for a girl's weekend before Maya's baby arrives. Meanwhile, Martin, still considering how to respond to Lena, joins Arthur, Frank and Henry in chasing after the women.
Lisa's unexpected pregnancy causes more complications than what Lena and Martin anticipated. Without Martin's knowledge, Lena decides to help Lisa despite her insistence about not wanting them involved in the baby's life. Meanwhile, Mae and Mason try to force Lena to admit that she and Martin are back together. After Maya's false labor scare, she returns from the hospital and is put on bedrest by Frank who insists on taking care of her.
Martin grows suspicious of Lena's strange behavior when she begins sneaking out of the house to secretly help Lisa Apple with her baby. Lena tries to avoid Martin but feels she needs to tell him the truth about her arrangement with Lisa. Meanwhile, Martin takes Mae on a driving lesson, which turns into a hot pursuit.
Lena and Martin announce to the kids that Lisa Apple's baby, Annie, is their half-sister, and Martin is surprised when they aren't interested in meeting her. Lena feels the burden of being stuck in the middle between Martin and Lisa but still offers to help bring both families together. Meanwhile, Mason overhears Lena and Martin's conversation about Lisa's financial difficulties and decides to start a fundraising campaign to help. Elsewhere, Lena feels a bit of empty nest syndrome.
In an effort to connect with their kids and bring the family closer together, Lena and Martin plan a fun outing, only to be interrupted by a blackout. Elsewhere, Lena urges an overdue Maya to get induced but must succumb and honor her birthing plan. Meanwhile, Martin continues to try and figure out where his relationship with Lisa stands.
Milo complains that Grandparents Day is coming up at school and doesn't feel Henry is interesting enough to participate. Lena and the kids urge Martin to reconnect with his long-estranged father, Brock, to rebuild their relationship. Meanwhile, Lisa continues to struggle financially and considers moving back home with her parents. Elsewhere, after listening to a true crime podcast, Maya worries that Frank has a dark past he has been hiding.