Because that guy originally had the same hair colour as his wig (I think so) and the girl next to him is his divorced wife but they haven't told their family. Maybe his ex-wife didn't know that he coloured his hair or maybe they are going to meet their parents or something so he wore that wig and ring.
I am not completely sure but I think that's the scene. Hope this helps (・∀・)
Soo from my understanding, he died his hair silver to look like the MC when he had temporary silver hair. The girl next to him was his ex wife, and so they both wore their rings to look like they never got divorced. And then he had to put on a wig bc he didn't want to be seen as extra in front of his ex wife or mom. I think he's doing all this to appear "normal" in front of his mom. I'm assuming that he came out to his family before but his parents didn't like it so he decided to get married to that girl. But he hides his true self with the wig and ring. This is what I'm understanding but i could be wrong!
Can someone explain to me chap 66 ? I don’t get why that guy wear wigs and ring and a girl next to him?