Can someone help me

What part you don’t understand?? For me to help you

I don't understand what Yeon-woo Jeong did wrong and why they are seeing things in the mirrors

Ok so nothing up to this point has been really explained, so maybe that’s why you’re confused, but we all are xD , anyways, they haven’t really said anything but it seems that Yeon woo has to do with the murders of his parents and now the uke’s friends , because Tae Yoon asked him and he admitted he killed all those people. They weren’t talking and had a fight because Yeon woo admitted that to Tae Joon and also Tae Yoon confesses he liked him and Yeon Woo said “what does that matters? Is that what what’s important to you”, so basically he didn’t care about Tae Joon feelings so that’s what he did wrong, and also the murders. The thing they see in the mirrors hasn’t been explained yet, we only know that they see things in the mirrors since they were little, but they haven’t explained yet what does that mean. I hope this helps ;)

thank you very much, you helped me a lot. And I'm sorry for making you write so much

You’re welcome and it’s okay haha, it is I that talk too much