Short answer: No ntr.
As for cheating, only on the guys' side and optional:
In 2 episodes, you can choose whether the respective male "MC" has an (off-screen) partner or not, but that's just a flavor choice with no further consequences, apart from minor dialogue changes.
That being said:
This plays in the original universe that the Garden of Venus universe was spun off from, and in this original, Sarah is a promiscous freebird, so 2 of the 6 episodes involve her. Those episodes aren't connected; each have their own male "MC", plus it's just flings, nothing romantical, but I guess this might not be to everyone's taste.
So, no ntr or unavoidable cheating, but I can't guarantee you'll like the game.
It's pretty short though, and the episodes can be selected independently.
Up to you.