Huge thanks for the detailed feedback!
Mike is intentionally designed as a total jerk, mostly to motivate the player to take revenge on him. We also don't plan to include any more NTR rivals in the game for a few reasons.
You're right that Akira is the main focus for NTR, however, I'm actually working on Rose NTR events right now! For Rose and other companions in the future, the NTR content will be linked to the Akira-Mike love progression.
I really like the idea of "hidden NTR," and the Rose events I'm currently working on are built around that exact concept!