Riiiight...
This is a VERY reductive way to see this.
Let's say, that like me, you chose the younger man.
After a while you realize that if you got the older woman, the older man got the younger ones. It then becomes obvious that if you are fucking one, he is fucking the other 2.
This is made even worse, because you are locked in a route. You can't see or know anything about it. But you can imagine it, not as a MC, but as a player.
To me, and I point this again, TO ME, this is very uncomfortable.
This HAS to be the purpose of this specific (horrible) game design. Make you imagine what is happening with the ones you can't see, cause frustration, making players uncomfortable, while delaying sexual gratification as much as possible.
I'm done being teased, I'll only ever play this again when (IF) it is Completed. This is waaaay too manipulative.
Peace