There isn't enough story there to detail it. Sabrina you go into a cave, win a fight that rescues her. Wait some days for her to heal. Solve a puzzle a day for three days. Talk to her in her bed five or six times. Quest completed.
You can decide if she is a virgin one night, decide if she has a dick another. Nothing else to it.
As far as Isha and Athia, you get magic spells if you side with Isha (Gwen) yo get the dialogue of Athia's love route if you side with her. Read through both walkthroughs, you will see there isn't much difference between the routes. Neither one have big story arcs.