Joongi mentions offhandedly that he likes a girl with strawberry blonde hair in a conversation with Lucas. If only to make it not obvious that he likes Rose. 

As a result, Rose ends up dying her hair a couple days later. Much to his surprise not that he puts two and two together.

.

She confronts Joongi about him being a supernatural only to begrudgingly admit that he was the only that jumped in to defend her because he couldn't deal with losing her especially after already losing Hyeri.

Either she can console him in a friendly sort of way or maybe they argue a bit more?

 

Joongi's personality rubs off on Rose's own causing her to stand up for herself much more. Which surprises everyone including Joongi himself. However, he notes that she's been acting differently around him which causes him a bit of concern. Especially because he hasn't been spending as much time with her causing him to invite her over when he's having a couple of drinks with everyone.

However, she's still somewhat distant which only heightens his concern and anxiety. He comes to see why when a couple drinks later with some egging on from Lucas and/or Siyeon when Rose corners him in front of everyone. All he can see is the heat in her eyes and for a moment he's worried because there's definitely some anger in there as well as a snarl etched into her face. 

He's worried that she hates him now and his gesture was all for nought only for her to roughly grab his shirt and pull him into a kiss.