Kamisawa cuts the red string of fate for a living, but he himseif is tied to no one, doomed to fall in love with people who will ultimately leave him for their fated people. When Hara comes into his life, Kamisawa knows he will only be hurt despite Hara's promises and tries to pull away.
This is about fate vs. choosing your own fate.
This is being continued, and guess what...the red string has appeared. They need to go through this, so this is good.
ETA Jan 2022: It seems we've reached the end! Things worked out okay for them.
Kanawanu Koi no Musubikata