I don't agree with the edit, The side ship sure is cute but gets quite boring pretty fast. The guy is literally emotionless / kuudere (having reacted only once when the girl declares herself as his GF)and the girl doesn't get that flustered (at least not easily IIRC)
How do they have better chemistry? Because they have both exp ? lol. I actually don't see it at all, It seems they are just dating out of convenience
The main ship never gets boring, though it lacks development recently, partly because they had to put this sideship with so many pages :/
I would prefer if they did a separate manga about them and focus on the main one here
TLDR: The main ship is the cutest .