Leah will probably walk in on them and catch Sophia showing her boobs to the boys. Then Leah will either join in, because she is the prototypical perverted older sister, or tell on her, thus getting her fired. The former will speed up Sophia's corruption, because like everyone else in the game Leah is perverted and trying to seduce Sophia. The latter leads to Sophia not having a side-job anymore, which means she has to figure out another way to get money.
So basically, we're definitely getting new routes one way or another.