In summary, Dew ends up buying the condo, and moves into Room 609. He continues to meet the parallel universe Mum and falls more in love with him. In the meantime, his engagement with Mint carries on, since he didn't break it off immediately, which causes him to start ignoring her and distancing himself. Feeling heartbroken, she goes to stay with Mum in Khon Kaen and tells him Dew bought the condo.
Furious for hurting his sister, he leaves, already guessing what the problem is, and goes to the condo. He goes during the time the parallel universe Mum is there. He starts yelling at the other Mum in the room (or at air since he can't see the parallel Mum), for appearing in front of Dew and ruining his sister's happiness. That Mum apologizes and says he can't not fall in love and want to be with Dew. He vanishes at 1:05. Mum then punches Dew. He wants to punch him more but can't. Dew cries and apologizes, saying he couldn't control his feelings. Mum begs Dew to be happy, marry and love his sister forever since it was his choice to agree to date her. Mum also admits he tried so hard this whole time to control his feelings since he also loves him.
The scene cuts to Mint trying on bridal clothes and texting Dew to ask his whereabouts. He texts her back and says he can't marry her. He monologues that he can't live a lie anymore. She cries, but is shown riding in a car with An and Joey, embracing her new single status. Parallel Mum is shown in the condo, and he monologues that everyone has choices, and he chooses to stay by the side of the person he loves forever, if possible, though he doesn't know what will happen next. (The same words Mum says on stage to Dew before singing at the end of episode 11.2). He then plays the guitar and sings a song he wrote for Dew, the drama's OST, but he does in a sadder tone than Mum does in episode 11.2. Dew is outside the door and hears it. He cries outside the door, obviously conflicted. Then it ends.
So, we don't know really know what happened to Mum or what he decided after barging into the condo. It did show him briefly after, talking to Ton, but not much was said.
As for Game and Vee, during the episode, Wee had run into A. He helped him and A kissed him, but he pushed him away. Game had seen them together and assumed Wee wanted to get back together with A, so he started acting cold toward Wee. Eventually, Wee confronted him about his attitude and cleared up the misunderstanding. Wee said he was ready to move on and be with someone else (Game), basically defining their relationship even more.
Sorry, that response turned out longer than I intended.
