You just need to solve the milkshake mistery to start having fun with the Best Friend, popularity is mostly for the stream income
After the milkshake you will have to keep visiting the BF in the dorm, talk about sex a bunch of time then you can date and have all the fun you wanna as any other characther
Most welcome, if you're still a virgin the BF would be really happy to help to solve the issue and romance will go up a little with BF, but you can easily romance the BF as any other with hang out and date (those will works also before the milkshake, but still no sex till the milkshake mistery is solved)
You can start the milkshake once you notice the taste of it (if you're playing as girl, as those should be just for them cause the Rich Boy rule the machine) or when you got a different text once you enter the party (if you never tasted the milkshake as girl or playing as boy), you will need to go inside where the restroom and snacks are located and check the noises coming from the room
After the discovery of the secret ingredient you wanna talk to the BF, go out in the main room and you would probably notice the BF has a milkshake in hand.. act fast!
