Responses
To be petty, also because they look alike so because the uke and seme stopped talking and according to the seme the uke would reach out first after firsts like that. It seems like the uke was either giving up on seme or waiting to go back to him but then saw the sister and decided "Well, can't avoid me if I get with the one person you have." Or something like that.
Can someone explain this, sorry spoiler
Why the uke choose to date the seme's sister, i didn't get it ?