You do realize this is a porn game, right? Realism isn't exactly par for the course. That said, it's often true that the more realistic the game is, the more enjoyable it is as well. (It depends on the game, though.) You already start off with an unrealistic premise: Nicole wants the MC out of Chloe's life, but she agrees to "payments" to keep him away from her daughter. What mother would actually agree to this IRL? Really, all for the sake of her daughter getting into a great school? That's more unrealistic, I think, than the transition into a love story.
And oh, what a beautiful and heartbreaking love story it is! Nicole loves her husband deeply, but he doesn't love her back, and even insults her often. Meanwhile, if you've kept Chloe as a girlfriend, there's the added guilt for both Nicole and the MC of the cheating they are doing, stabbing her in the back. Even if you corrupt Nicole and don't go with romance as much, there still is the pain she feels over the loss of John's love. (And what's worse, the player knows that John may never have loved Nicole; if he ever did, it's been a very long time.)
Combine this with other characters and their own struggles, and you have a pretty interesting VN: Nessa forced to pleasure clients for her future with Natiya; Abigail in a loveless marriage with a manipulative ass for a husband; some secret Hal and Jenny are keeping from the MC that apparently will devastate him; etc.