I'm still dying from this tbh. I stalked Jellyfish's page forever waiting for the music video after the album release. Now when I watch the music video or listen to the song, it doesn't feel real at all.
Theory:
Since it is connected to Dynamite and the crashed a wedding in Dynamite, this is the prelude to Dynamite. The envelope that Leo had passed to N was the invitation to the wedding and Leo or N are in love with the bride. The fantasy was where they were happy with said female, however we have yet to see that fantasy (which probably be the third installment of the trilogy). At the end of the chorus, Ken says, "Please save me, fantasy" and N is seen going towards a white door, with Hyuk trying to stop him from entering. After being heartbroken, he wants to enter his fantasy but in doing so, he would be avoiding his cruel reality. In avoiding reality, we see what he and Leo's reality is, as they are tried up to a chair but only Leo is desperately trying to escape, his captor making some sort of red concoction in the background. Originally, it would have made sense that the captor was a female, like in voodoo doll, but it is a man. Is it the finance/ groom from the wedding in Dynamite? He possibly realized that N and Leo were in love with his wife and wanted to get rid of them. So are both Leo and N lovers of the bride? Going back to 2:03, Leo and N stand on opposing side of a mirror, showing that they are one person but two different sides of the person. N is the side that wants to stay in his fantasy (he doesn't fight when he is tied to the chair) and Leo is the side that wants to fight off the challenges he is facing in reality (he was fighting get out of the chair and hiding in the woods). At 2:52, Leo is seen wrapping up his hand and covering up the symbol on the back of his hand (the symbol that was also on N during Dynamite promotions). The symbol is most likely the after effect of the red liquid and he is covering it because he doesn't want it to effect his life. The anger, however doesn't set in until the end, where the video ends with Leo sitting in front of a dinning table in some sort of hall, dressed in all black with the eye patch on. In most cases, anger leads to jealousy, make Dynamite the actual second (or third) part to the trilogy where they crash and destroy the wedding.