The following Friday, Abby and Simon arrive at the Waffle House first. Martin arrives a few minutes later, promptly destroys Abby's house of sugar packets, and announces he forgot his script. Both Abby and Martin have their lines better memorized, so Simon's mind wanders to Blue. He's pulled back to real life when he hears Abby telling Martin "no." Martin is kneeling in the booth, belting one of the songs from Oliver. He sings the entire thing as everyone in the restaurant stares. Abby hugs Martin when he's done, which makes Martin smile hugely. Simon smiles back and wonders if they're actually becoming friends.
It's worth noting that Martin's impromptu performance is something he undertakes fully of his own volition, without listening to Abby—in short, he's showing Simon exactly the kind of agency that he took from him by blackmailing him. Simon seems unaware of this and seems far more interested in what this tells him about Martin's character, which does suggest that Simon is becoming gradually more interested in other people as time goes on.
Two hours later, as Simon and Abby climb into Simon's car, he feels strangely electric and excited. They listen to Leah's birthday mix and discuss that while Martin is cute, he's not Abby's type or Simon's type. At a red light, Simon thinks about Blue how is telling Blue’s mom tonight that he's gay, and he asks Abby if he can tell her something. Simon swears her to secrecy and tells her he's gay. Abby is quiet for a moment and then asks Simon to pull over. She holds his hands and says she's not surprised, though she didn't know. She tells Simon she loves him and then they head home.
For Simon, the knowledge that Blue is also doing something scary tonight is enough to bolster him and give him the confidence to come out to Abby. This illustrates how his growing relationship and intimacy with Blue has the power to give each of them more confidence in their individual lives and push them towards bravely recognizing these hidden parts of their identities.