On the notion of soccer, maybe winning or losing a game can be dependant on player morale too. Not minmaxed, but certain specific games could have their outcomes changed by player decisions leading to team morale increasing or decreasing. These events will be mostly independent of each other except for major games.
Also, I'm curious as to why you didn't choose volleyball as that is the typical game associated with girls and especially in h games. But this creates an opportunity - a volleyball team could be introduced, and there can be contention with the soccer team. Maybe even some soccer team members could join it if it's a new team that starts in the next year, or you could simply have volleyball be in the time of year soccer isn't and make it an extra thing to join.
As for degree paths, you could give a limited number to choose from that are generic, like Liberal Arts, Sports, Technology, and Fashion. These classes will change the MC's personality a bit as time goes on and lead to more or less events in different places in the future (gym, Cafe, dance club, robot fighting club, etc). Nonetheless, the protagonist isn't barred from content and still retains the initial athletic personality, it just skews in different directions.