Yes, it's canon through posts that they're friends with benefits who care about each other a lot. They posted relationship charts for every character, and Ais said he got TOO attached to Vere, so that's interesting!!
it's also implied Mhin and Leander have slept together at least once.
I also think it's cool to have a game where all your love interests are so involved with each other. I too wonder how the mc is going to change the relationship dynamics of the others.
here's the specific chart I was referencing btw.


