sorry i really like the idea of this
So, Keith is super oblivious.
But, Lance has never been in a male x male relationship so... He doesn't want to make the first move in case he does something deathly wrong.
Plus, Lance knows Keith at least likes men (and according to how he reacted to girls, Lance assumes he's gay but wouldn't put his money on it), so it still is possible that Keith has been in a relationship, right?
Keith doesn't know what the fuck is happening.
All of a sudden Lance makes him so happy, and he can't stop smiling when he's around him, and it's gotten so bad to the point where he avoids him EVERYWHERE.
Lance: Hey Keith, what're ya up to?
Keith: *Naruto runs out of the kitchen with food goo dropping on the way*
Lance: He's been spending too much time with Pidge.
Lance is fairly confused after that interaction, because Keith just seems way more pissed around him now and maybe he was wrong?
But also, Keith lived in a shack in a desert for a year, so how can Lance trust his social skills?
Lance-social-star-McClain can't figure out Keith and he's SO irritated by it because he even figured out the little gremlin had more backstory then they said back at the garrison. And honestly, they need a couple of lessons in social etiquette too.
So one day he confronts Keith, because he's honestly so Done™ with this shit.
Keith: *very distracted and not realizing Lance is talking to him* hm?
Lance: Do I make you uncomfortable? Or am I not tolerable? Because I meant those arguments in all good fun, y'know, like friendly teasing and stuff... And, well, you... you've been avoiding me.
Keith: *staring him in the eyes, face slack with shock*
Lance: WHAT DOES THAT HAVE TO DO WITH ANYTHING?!
Yes, Keith had a gay panic and honestly who could blame him because Lance was just so sweet and vulnerable to him and wanted to make sure he wasn't bothering him and Keith is just so whipped.
Lance looks really hurt after Keith has no sign of saying anything else, so he starts to retreat, slumped and radiating a depressing aura.
And a sad Lance is a sad Keith, so Keith needs to stop this now.
Keith thinks maybe he's homophobic or something because he's oblivious as hell, so he tries to make sure they're okay.
Keith: If you're homophobic or something that's okay, I'm sorry I said that all of a sudden and I don't want you to make you uncomfortable-
It's then that Lance turns around.
He's gripping his left arm in a slumped position and his head is hung low.
But once Lance looks up Keith's heart is shattered into a thousand pieces.
Lance's face is tear-stricken and his eyes already have red rims. He has this sad smile on his face, and his eyes shine even more blue than normal. Keith shouldn't be appreciating the fact that he made Lance cry but oh my God he's gorgeous when he cries and honestly who can be gorgeous while crying? But Lance's eyes. The water from the tears swims around in his eyes, and what normally would be a shallow beach in Cuba is now the deep end of a New York port on a stormy day. It makes him gorgeous, but it makes Keith's heart ache.
Lance: First of all, I'm not homophobic.
Lance: Second of all, I... I'm just upset because you've been avoiding me and... you seem to be really mad at me... Honestly if I did something wrong, please let me know and... Even though I don't know what I did, I'm sorry.
Meanwhile Keith is having a huge internal panic because oh God Lance thinks he hates him but he doesn't know what to do so he says the first that comes to mind and...
He's taken aback by his own statement because is that what it is? Is this what liking someone is like, is that why his heart feels so full near him?
Lance stares at him with wide eyes because what? Oblivious Keith™ knows what liking someone feels like and ADMITTED to it?
Lance: Are...are you being serious?
Keith: *looks Lance in the eyes*
Lances eyes are like the ocean, and he's the sand, because he keeps getting drawn back in over and over no matter how hard he tries to get it to stop...
But honestly? Keith doesn't care.
Because as long as he's with Lance, he's safe.
(and yes, in case you're wondering, they started dating shortly after that.)