Keith and Lance are both very dense.
Keith will stare at Lance for their whole dinner, grinning stupidly, and Lance is all like ‘he’ll never be mine’. The first time Keith put his hair in a ponytail, Lance ruined every training exercise because he couldn’t help but notice how bouncy it was. And if Keith shows any skin, Lance will hurt his neck because he keeps turning his head to see Keith, but then looks away because Keith’s too hot for him. But Keith is completely convinced that Lance hates him. So they just gaze at each other lovingly for months when they think the other isn’t looking, until Pidge and Hunk lock the both of them in a supply closet.