[His thought process screeches to a halt when he realizes he's dwelling, and now she's dwelling on something she shouldn't dwell on, and so he forces himself, forces himself to stop thinking about it.]

It's, it's fine, s'in the past. Besides, gotta focus on what's here, and now, and...saving the world, or...whatever. [To try and derail further:] And you know, the stuff here, it's nice, nice people, mostly, so don't worry, and, you know, this place'll be right in no time if we all just, uh, pitch in, so you'll get back for your Regionals, see your friends and boyfriend again, it'll all be fine.

[It sounds like he's run out of breath after that ramble, so he just takes a deep one and Lucemon:]

I think Campbell's telling you to smile!

Yeah, that.