After Darby runs into an old flame and his new girlfriend, her best friend Sara, who's eager to bail on her long-term boyfriend Jim's family obligation, convinces Darby to join her at a coworker's rooftop party. After hours spent stalking her ex's new girl on social media, she winds up connecting with an overeager, romantically bruised.

When a therapist encourages her to address her fear of rejection, Darby recalls being 15 and applying to boarding school to get her parents' attention. When she's stranded there for Thanksgiving break, an encounter in the dining hall plunges young Darby into a blissful week with too-cool-for-school Luke Ducharme. But Luke becomes aloof when the student body returns to campus.

The girls head upstate to celebrate Mallory's engagement. At the cabin, Darby struggles to get through to Sara as their paths continue to diverge.

After a "serendipitous" reunion, Darby and Augie find themselves falling into a comfortable, full-blown relationship (again). However, Darby is soon left wondering whether "comfortable" is enough.