[She's not entirely wrong, really. He's only half-listening for a short while, upset and anxious and actually a little mad that he's not making any kind of traction to finding Baymax but there are a couple of key words in Ruby's explanation that finally cut through to him.

'You're doing that thing where you act like you're fine when you really aren't.'

But...]

That's what I have to do right now. [The words are quiet and not exactly something he'd planned on telling her, but nevertheless they're true. Still, it snaps him out of it and he blinks heavily, vision clearing and he's staring at her like he's just now realizing she's really there.] Ruby? ...I really almost made a huge mistake, didn't I?

[He's still itching to run and fix everything, but at least he's starting to calm down and really come back to being logical.] Sorry, I didn't...[A beat.] We really do end up sitting on the ground alone together when we're having really serious discussions. [It's not meant to be answered, just a repeat of exactly what he said to her in the jungle and maybe, just maybe, there's a bit of a tighter grip on her waist once he realizes just how serious this actually was. He shakes his head then.] I really wish they'd stop finding ways to mess with our heads.