I believe he means, or is rather begging Kangmoo to hold back his urges. You can see throughout the side story that Kangmoo is slipping and it’s getting hard for him to resist his murderous urges. If he succumbed to such urges it would turn everything in their life upside down. Hence why Kirin begs him to hang on. I’m probably explaining it terribly, it’s something so nuanced and complicated, which is to be expected considering their relationship though
You explained it correctly. If the OP spared their time to actually read the story, they would have known this bc the Author herself explained it! And the uploader even posted her reply.
okay i would just like to ask, what did kirin mean by 5 years or 3 years? at the part where the seme looked as if he'll go into a murder spree? enlighten me fls