@Damia98 fairly certain onee-chan already knew she liked the guy who looks the same as the japanese twins. The last arc has pretty much been all about whether she dares commit to her love, or if she should make sure she is ready to go home with her little sister twin when its time.
I'm a bit surprised imouto-chan twin expressed her doubts about whether its the right thing to be with the one you love, if you have family elsewhere. Thought her opinion was that romance took precedence and that onee-chan shouldnt worry about her. Also been getting vibes that little sister twin always intended to stay in the other world and that it would be a non-issue if onee wanted to as well, but this chapter makes me wonder if she intends to go home after all.