The translation here is bad.
I think its:
Spoiler!
Yul: "Hey, listen, I'll just be your sl** from here on out."
G: "Excuse me?"
Yul: "I'm Just a piece of trash sl**, you said so yourself. I'll be yours."
G: "Why the he** are you treating me like him?"
Yul: -startle-
G: "Alright, so now I'm more pis*** than I've been in a long time."
Note: Him is probably referring to the dude that keeps texting Yul and not Seo.
