Xinlu and Yuri have different way of loving someone. And with how it ended with Taeui I think it's only natural for him to want someone who gives him their full attention.
What he craves for is passion and commitment. It's like an agitated sea.
On contrary to Yuri who loves someone as steady as a calm sea.
Xinlu doesn't declare his love for Yuri but it's pretty obvious even to the oblivious Yuri.
If I remember correctly Xinlu did tell Yuri he would never love him romantically but that's in the beginning when he was crazy about Taeui.
When he says that he would kill anybody who loves Yuri is near the end of the novel so it's pretty unfair to put this two sayings in the same sentence when there's a gap in time when Xinlu said these.
Hahah you had me reread all of the last few chapters to identify the passage you were speaking of, and I didn't find it nor have I never read anything along those lines. Maybe you're referring to the part when Yuri asked if Xinlu liked him after the latter said he didn't like it when something he likes gets taken away from him? Or maybe the part where he says he could never like someone the way Yuri likes someone, because it's like "chewing on bland grass"?
All in all, like others have explained, Xinlu said that he could never like Yuri the way Yuri liked him. He is greedy and possessive with the person he loves and cherishes them in a manner that is totally different and way more intense. However, you can very much believe that Xinlu love Yuri deeply, since in the bonus tracks, he even tells Taeui that he is thankful Taeui left him, for he now has the person he cares about the most in his life.

is xinlu the "look at me and only me" type? i need motivation to continue reading because he's really getting on my nerves
haven't read the novel yet so i want to know if he was the narcissist type and want yuri's full attention in his ://