The episode begins and Nick and Robin are starting to drift apart they haven't had sex in three days. Robin blames Marshall for having pulled Nick into his basketball league. Nick pulled his groin. Lily starts to get awkwardly excited about the icing about a man icing his groin. Ted mentions that he's also part of a basketball team made up of architects: The T-Squares. Robin says that now that she and Nick aren't having sex, they're talking more and she's noticing that Nick is "kind of dumb". The rest of the gang has noticed this, as well.
They say they started to notice when Nick he was trying to do a crossword. He asked for a four-letter word for "cut," and when everyone suggested "nick," he kept asking, "What?" Then he wrote down "shave". He also once made a quip about gypsies being as real as trolls or goblins or dolphins. Barney tells Robin to dump Nick, but Marshall stands up for Nick, because he is a human being with a heart. Robin realizes that Marshall's worried about throwing off Nick's basketball game if she dumps him. Marshall responds, "Robin, he had 36 points and 17 rebounds last week and that was with his shoes on the wrong feet". Robin shows up at the bar and tells the gang that she tried to break up with Nick but he had his shirt off so she decided to watch him do sit ups instead.
Barney has a real way to get Robin to break up with Nick: An invitation to Robin and Petrice's "BFF Fun Day". Petrice is a co-worker of Robin's who'd become obsessed with her. But if this invitation went out, "she'd latch on to Robin and never let go," Old Ted tells us. Marshall asks Robin to let him down easy. Barney suggests taking Nick to Splitsville, a dessert place down the street where everyone goes to break up. We see couples at tables crying inside Splitsville when Robin tries to break the news to Nick. She tells him they should maybe not see each other anymore, and he thinks she wants to turn off the lights while they're having sex. Then she tells him, "as a couple, we're not working out," and he thinks she wants to start going to the gym together. Nick's phone rings and he cries after taking the call.
He tries to pull it together and asks Robin what she was going to say, and she tells him, "I was going to say order whatever you want. It's on me". Nick says he's rather just eat it out of a bowl. Ted comes to the apartment and reports on the T-Squares' first game. It came down to the last second and Ted "saw the space in a way opponents never would." He bounced the ball between one of the defender's legs, working all the angles against several walls before the ball went through the net. His team lost 112-2, but the two points were taken away because the ball went, as Ted sarcastically says, "out of bounds". Robin calls from the restroom at Splitsville and wants to talk to Barney, who is sitting on Marshall's back while Marshall does push-ups.
Marshall is working out around the house so that he doesn't turn into a chubby dad. Lily, by the way, is trying to turn all of her friends' stories into sexual fantasies. Robin tells Barney to delete the "Robin & Petrice's BFF Day" invitation because she tried to break up with Nick, but he was devastated by some bad news and she thinks a family member might have died. Marshall is excited by this development. Barney says he'll only delete the invitation if he hears Robin on speaker phone. Robin returns to the table and Nick apologizes for crying. His doctor gave him bad news his MRI showed a big tear in his groin and he's going to miss the basketball league playoffs. Lily is "listening," Ted thinks it's "sickening," and Barney is "exiting".
Back at Splitsville, Nick tells Robin that now that his groin is going to take a while to heal anyway, they can have sex again. He starts kissing her neck and she's into it, but Barney shows up and tells Nick they can't stay together because he and Robin are still in love. Barney tells Robin he's taking care of something she can't do on her own. He tells Nick that Robin doesn't want to hurt him but she thinks he's stupid and she hates him. Barney goes on to declare his love for Robin, saying she has a hold on his heart that he could not break if he wanted to and he has wanted to. He says he is "hopelessly, irretrievably in love with her more than she knows." Nick asks Robin if it's true and she says, "You heard him." Nick says he feels like he has a pulled groin in his heart.
Nick starts crying and two hot young ladies are also crying after having their hearts broken, so the three of them head off, weeping, to Nick's place. Lily wants to hear more of that story and Ted finally asks why she and Marshall aren't having sex. Marshall explains the "uncanny phenomenon" that began after Marvin was born. They're always tired and Marvin cries from the other room every time they're in bed and start kissing. Ted picks Marvin up and decides to take him for a walk so Lily and Marshall can have some "private time," They claim they can't just have sex on command, but Ted's outside the door for just a moment when he comes back for Marvin's diaper bag and Marshall and Lily are already naked on the couch cushions, which are already on the floor.
Walking home from Splitsville, Barney gives himself "the Oscar for Best Fake Romantic Speech". Robin tells Barney she didn't need his help, but she tells Barney that he was pretty convincing. Barney cracks another joke, but Robin isn't joking. Barney says he was just "bro-ing" her out. If he had to tell the story any longer, he'd have had to kiss her. It seems like that's what is about to happen when Robin's phone rings.
It's Petrice. She got the invite. "You know what I forgot to do?" Barney says. Then snapshots of Robin and Petrice are shown on their "BFF Day" getting massages together, eating ice cream together, and riding a ferris wheel together. The last picture is of Petrice alone atop the ferris wheel looking down with a shocked look on her face. The episode ends at this point.