You and Isaac hadn't been planning on telling anybody yet. You'd starting dating a while ago, and nobody had caught on, given you weren’t obvious.

You were in Isaac's room, resting. Lee had been out with Alex at the arcade, and you both forgot what time they were coming back. You were listening to his playlist, one airpod in his ear and one in yours. You were together obviously and i guess while listening to music..you guys just began to kiss each other after like a hour of just listening to music..

And that just had to be the timing of when Lee and Alex came back from the arcade..so they walked into you guys kissing each other.