I don't understand people who get confused about this "incest" thing when it's not incest. They are not blood related so it's not incest. It's only incest if you share a blood relation to the person. Also why would you think it's not going to include Yuri it's clear he said he wants all 3 and they have agreed to it so what's confusing you?
So imagine a guy let's name him Tom. Tom has an adopted older brother that had been with him since birth. Theygrew up as normal sibling, treated as such by their parents Eventually when Tom is 20 he decides to marry his adopted older brother. How is that situation any different from blood related incest???
You can be raised to fuck your real brother as if it wasn't incest but that makes it incest, just because you grew up as siblings if yall aren't blood related it doesn't make yall siblings yall tell8ng yourselves is incest is some form of mental kink or something of trying to see this as wrong when they aren't siblings. Let's turn this around. Say tom is my half brother and I never met him, but then I do but I fall in love with him. By your logic, it shouldn't be incest.

I’m begging you, anyone, please tell me he doesn’t get with Yuri… I was scared it would end up like that but I held onto hope that he wouldn’t, please tell me he doesn’t at least consensually be with Yuri.. don’t make this an incest story PLEASE TT