Of course she's enjoying the sex. The situations Tatsuki witnesses wouldn't be nearly as exciting if the possibility of losing the woman he loves wasn't on the table.
That said, the dudes that think Hana will end up becoming a cock slut mostly trying to believe their NTR fetish is the reality of the game and that just betrays the entire concept of Hana's character being that loving wife to begin with. I thought the appeal WAS the fact that Hana does these things for Tatsuki that made the entire thing fun and exciting?
I have no idea what Fallen Eros ultimate plan for the game is, and maybe a NTR ending is possible, plus the dude obviously loves money so if enough desperate patrons demand NTR I can't see him not doing it. I mean Hitomi's dev basically turned his awesome hetero NTR game into a gay game because he got paid though I want to believe Hana's dev has a bit more integrity than succumbing to the cheapest NTR situation because some dudes are willing to pay to see a character everyone else loves get corrupted.