I'm so glad you're enjoying the game! It's more a dating sim than a sex simulator, though I plan to offer plenty of opportunities to hook up if the player wants to.
You can play the field early on, but later down the line if you form a closer relationship with someone you can ask if they want to date (or they may ask you). Some guys only want monogamy and some are into open relationships. Some guys aren't ready for/looking for a relationship. And even with sex, some guys are open to immediately hooking up and some need to be worked up to. So just like these early parts, each guy has their own desires and wants.