
"it's nice to be alone"
Can someone explain this part to me? (╯°Д °)╯╧╧

Kanao made a deal with neighbor Konno, Sei made a deal with Kanao's brother Kaoru to get the neighbour out of the way, that's him texting Sei. Sei knew that Konno was still watching the couple do the devil's tango so he said "it's nice to be alone" since Konno couldn't watch them when they were on a vacation. They're both manipulating third parties to keep their significant other by their sides, but in fuvked up ways.
We all needed this chapter.