Yoongi always played cool with him. He could transform in a goof ball just for him in a matter of seconds. This was their intimacy. This was Yoongi showing him a part of himself he does not show often. 
Little things like squishing his cheeks would often get him in a annoyed mood but somehow when Jungkook did it he couldn't help but smile. 
The kid was so cute. Much to Yoongi's pleasure. He had big teeth and loved plain white tees so Yoongi made sure to write a song about it. To be honest he had a dozen and more songs dedicated to small details about Jungkook. Details only him could see. 

-What are you thinking about?
His gentle voice interrupted his thoughts.
-Pizza. And sleeping.
There's no answer. In fact Jungkook's been pretty quiet. Quieter than usual.
-What's wrong? 
Jungkook bites his lip and Yoongi knows this is a big one.
-We just fought, again.
The evil better known as Jungkook's girlfriend keeps messing with the poor kid. If Jungkook allowed him he would fight her with his bare hands even thought he is sure she would put his in his place. 
-Spit it out already.  
-She's just... jealous.
-Jealous? Is the dumb?
Jungkook is not the type of dude that plays around with other girls, especially if he has a girlfriend. Definitely not a player. 
His words gained a death glare from the younger.
-Ok ok I won't call her a again.
-That's what you always say... and you're not helping Hyung. 
-Ok so let me see... who is she jealous of?
Jungkook hesitates for a minute. 
-You.
Yoongi's mind is now blank. He panics. Was he that obvious? To the point where his girlfriend realized?  Jungkook was too naive to tie the knots but his girlfriend actually caught him.
-I'll talk to her.

Catching her on the hallway was rather easy since she was too loud.
-Hey. Can we talk? 
Even Yoongi is ashamed of himself for treating her this good.

They end up in the empty classroom near wing B.
-I guess you talked to Jungkook.
Her perfume is driving Yoongi insane. It's unbearable.
-Yeah yeah I did. What's the whole deal with that?
Yoongi is trying to play it cool but this is Jungkook's girlfriend we're talking about and her arched brow speaks for herself.  
-Do you think I'm stupid Yoongi? You think I don't notice the way you look at him? You can't play me.
There's nothing to say. Yoongi knows damn well its pointless to deny it. 
-You know he is like a little brother to me.
-You don't look at your "little brother" like that.
The little emphasis she made makes Yoongi sick. 
-Like seriously how insecure are you? Listen I just happen to be his best friend okay? You don't need to worry about me. And you know damn well Jungkook would never cheat on you. 
He manages to slip his deepest voice to make it look like he means it. 
-Of course Jungkook would never take the iniciative. But you would. 
-What kind of person do you think I am? 
Yoongi is truly offended and those are probably the truest words he has said so far.
-I don't know but you're crazy for the kid so God knows what would you do.
Yoongi rubs his temples. 
-I seriously cannot believe you. You're truly one of a kind. Listen I don't give two flying s about what you think about me. Just stay in peace with the kid and that's all.
-So you're telling me stay in my lane? While I clear the way for you? 
-Jesus Christ you are legit a total . Like I said before you don't need to ing worry about me since I'm dating Jimin so shut your mouth already. 
Is Yoongi dating Jimin? Hell no. Jimin is actually dating the new guy Taehyung something. But this was his scape goat.
-You're dating then?
-Well if we speak the same damn language that's what I just told you. 

Yoongi thought this was the easiest solution to the current situation but it just got worse. Jungkook has yet to contact him and he's been avoiding him while making sure to show off his lil side hoe. Not really a hoe... just his girlfriend and meanwhile all of this is happening, Jimin also noticed a change to the point where he is asking Yoongi. 
-Suga what the is going on?