A threesome sex option is required
Viewing post in Course of Temptation comments
There are a few threesome scenes if you have the slut inclination, are part of the swim team, or if you are polyamorous and have at least 2 partners.
For the slut inclination: You may get an event where someone stops you in the hall of your dorm and asks you to have sex with their friend who is still a virgin. Then they and their friend double team you.
For the swim team: Don't wanna spoil it but keep attending practices and meets until the dress code for practices changes. Then practice will occasionally give you the opportunity to have a threesome with your teammates.
For the polyamorous inclination: Get 2 people to be your poly partners and schedule a group hangout with them. If they both show up it ends in a threesome.
Could be a whole lot longer unfortunately! It took me most of the school year to trigger it. Swim team is especially tricky because you only have biweekly competitions, and I'm pretty sure progressing that storyline is locked behind doing well in competitions.
You'll know you're on the right track when coach starts offering you one on one training, then demands you do something sketchy during one on one training. Gaining relationship with The Quietly Determined Athlete may speed things along but I'm not 100% sure about that.