Unbeknownst to Lena and to her dismay, Martin starts to date a familiar face and surprisingly begins to see the world of relationships through brand-new eyes. Meanwhile, Lena tries to show she's a good role model to her kids by proving a point and faking a night out on the town.

Martin and Lena are thrilled when they hear that Mae has won the lead in the school musical but are surprised to learn that she has been confiding in the school psychiatrist, Dr. Rydacto, about her feelings toward how not divorced they are acting. Meanwhile, Martin has reservations about how fast his relationship with his girlfriend is going and asks Mason for girl advice.

Despite Lena and Martin getting along as co-parents, they must determine the best way to orchestrate Milo's upcoming birthday festivities based on their new system of boundaries. Meanwhile, Oliver is pleasantly surprised when Jenna shares a birthday invite with an unforeseen guest. Elsewhere, Maya takes matters into her own hands and reveals a surprise guest of her own.

Lena and Martin choose to share the house for the summer while the children are away at camp despite Lena's reservations, but soon realize it might not be the worst idea. They collectively agree to throw their annual backyard pina colada party where they will celebrate their independence from their children. Elsewhere, a friendly face returns back home and Martin can't help but see it as

After Lena and Martin sleep together, Lena searches for signs that they are or aren't meant to be a couple; Arthur and Camille trail Lisa Apple, hoping to determine if she is pregnant with Martin's baby.

Martin finds every way he can to avoid asking Lisa Apple if she is pregnant; Lena worries Mason is changing himself to please his new girlfriend; Maya tells Frank a made-up story about a friend who is dating someone new.