I like that you get to a point pretty early on where the FMC admits (both to herself and to the MC) that she likes it. I think that's a key point and will help to move the sharing path along quite nicely.
There's at least one cheating flag set up already, but it's too early for that to be progressing yet. As with the rest of it, it's currently laying the groundwork, but it's already setting the basis for possible cheating (depending on choices made). I don't remember the specifics, but I think it was something like she liked it, but he told her it was too much, and you can tell that she wants more and might therefore go behind his back for it.
I didn't get any errors. A friend said he had a problem with coding, where he didn't pick an option but later dialogue said that he did. I didn't get the same issue there, but I'm going to replay from the start to check some stuff out and will see how it goes. Definitely no exception errors found though.
It's really early in the story still, but even so, there are already some differences noted based on what choices you picked earlier on. For example, if you picked the more lewd options initially, the FMC will be more open to making those decisions later, rather than needing MC to push her to them. It might only be dialogue (thought) differences there at the moment, but at the same time, you can pick the vanilla options and still get content later, it just comes down to how far you go and how fast.