Note: The following content is all originally from the G-BOM Baidu Bar, some parts omitted.

I've been lurking on the G-BOM Baidu Bar for a long time~ I truly feel that there is something fishy going on between GD & Bom from before.

First of all, during the GDYB+2NE1 performances @ SBS Gayo Daejeon 2009,
Taeyang & Bom performed You & I as a duet and even ended it with a passionate hug.
Many of you should have noticed that a certain someone had a very unhappy expression on his face when performing Let's Go Party with 2NE1~ I repeated the video, and finally found evidence that a certain someone was indeed jealous.

Let's take a look~~~~~

First, here is Bom~ Singing wonderfully ^^
Taeyang appears on stage...
Already holding hands~ Can imagine a certain someone's grumpy face, kkk 
Slowly closing the gap..
Important part right here!!! Taeyang slowly leans his face closer to Bom's, seems like he's about to borrow a kiss.
It does look like they're really about to kiss! From a distance, it even seems like they are already kissing.
(I watched quite a few fancams for a while (repeatedly) and made comparisons.)
This is what it looks like from afar, doesn't it look like they're already kissing..? (You will understand why I am emphasizing on this "kiss" that looks real from afar in a bit)
Take note of the golden background.
LEFT: where Taeyang and Bom are standing, RIGHT: where G-Dragon is standing
P.S: One of the important points, at the stage on the left where Taeyang and Bom have finished their performance,  GD & CL (who are on the stage on the right) are about to start performing The Leaders~ When Taeyang & Bom's performance was coming to an end..the shot was cut off to Jiyong..Jiyong was looking in Taeyang & Bom's direction with a totally expressionless face..what was he thinking about?
Turning his head..still expressionless..even pouting a little..
Jiyong discovers the camera..and still has no expression on his face.
We should all know that Mr Kwon will often make lots of expressions that are full of swag when he is performing..and rarely shows an expressionless face..
While 2NE1 was performing Let's Go Party - Jiyong who is at the side, is obviously absent-minded and unhappy. The "usual" Jiyong should be bobbing his head to the music or singing along like at '09 MAMA..why is he portraying such a crestfallen look?
Tilted his head backwards..not too happy..
This is photo is a bit laughable and cute. Did Yongyong sigh?
Looking over once he hears Park Bom's voice.
After looking at Bom, he immediately lowers his head..just like a boy who didn't get his candy. This expression is indeed a little unpleasant, don't you agree? Yong ah, even if you hide your eyes behind your sunglasses and we can't see the look in your eyes, your facial expression has betrayed you, kkk
Seems like Jiyong noticed that there are fans filming him..(thinking on the inside): aigoo, did they find out that I'm jealous because of Bom?
The certain someone who immediately sat up straight.
Immediately started grooving to the music..and revealed a slight smile. Mr Kwon, have you finally calmed down? Fans have already recorded your depressed expressions~

This is when my suspicions grew,
1. If Jiyong was not depressed because of Bom & Taeyang's intimate act (maybe he thought the kiss really did happen from afar), then why would he have that unpleasant expression? Jiyong doesn't have many expressionless times (on stage)..right?
2. When 2NE1 was performing, Jiyong still had unhappiness written all over his face. That's totally not G-Dragon's style~ G-Dragon would always bob his head to the beat and such, and at least he'd have a slight smile on his face unlike this depressed expression.
3. After looking at Bom, Jiyong immediately lowered his head and had an unhappy expression..I felt that it was pretty obvious from then on..take a look at the videos.

Video 1: You & I performance, take note of Jiyong's expressions at the end.

Video 2: GD during Let's Go Party

Video 3: This is the full video of GDYB+2NE1's performances.

More G-BOM moments during Let's Go Party performance:

source: 我要开始咆哮了@G-BOM's Baidu Bar
video credits: traterling@Youku
trans by: OMONAclaudia@Twitter
extra screencaps by misstjia@GBOMsince2006 - from the video below (cr: gdntop@Youtube)