They aren't dating.
To date—to actually say aloud that they're dating—is dangerous. Dating means repercussions at work, means doubts about letting them stay so close to each other in a profession where a moment's distraction could mean death. Dating means the kind of commitment that, if broken, ruins friendships. And she can't do that, not when this job means everything, and he can't do that, not when it means the risk of losing her.
So they're not dating. And if he places his hand familiarly on the small of her back when they're walking together, if she rests her head on his shoulder when they watch movies, if they occasionally walk arm-in-arm when they're not on the job . . . well, that doesn't count, because they haven't yet had that conversation where they put a name to this thing between them. And that works for them, for now, and they convince themselves that by not giving it a name, they've avoided everyone else's notice.
So it's lucky they don't overhear when a friend of Alex's asks about them at a barbecue. "So what's up with those two?" he asks, glancing over at their table.
"Syd and Gage?" Alex replies. "They're pretty much dating."