Glad to hear that you're enjoying the game!

And you went about it the right way by asking around when you had some reservations earlier. I also want to applaud you again for supporting the dev on his Patreon. Kudos!
(And kudos to other folks such as
Sorrow85 as well to always keep folks here in the loop on the latest news.)
I just want to reiterate what others have said such as
SpyderArachnid that sharing is optional regardless of the hero-villian dynamic. Kat will never stray -- not even off-screen -- if both the MC and Kat doesn't agree to green light it first. There will always be other ways to resolve situations like what
A.C.H.B. brought up earlier.
Limited20, you're good and safe. Remember, while there are sharing scenes in the game,
1Thousand has carefully planned it and takes his time in creating exclusive scenes that only appear on non-sharing routes (as you've obviously experienced in your playthrough).
Man, I need to get
back to this game again real soon. I'm a few chapters behind now. ^^" There's been a surfeit of decent games out there to try lately and only so many free hours in one's day to devote to that after all, hahaha.

Alrighty guys and gals, stay safe out there, and always pretend to be a ninja or something cool while wearing those masks out there during the pandemic! ;]