How could a 19-20ish year old man be subjected to abuse over 100 times? Please help me understand why he didn't walk away? I hope he reported it the very first time it happened.

there are many possible answers.

Predators are often very good at selecting their victims, choosing young people who are vulnerable for a variety of reasons. They may come from a dysfunctional family. They may be economically or otherwise at risk. There may have been drugs or alcohol involved, in which case the victim feels unable to come forward for fear they themselves will be punished for breaking the rules. And after the abuse happens once, the perpetrator will often threaten to claim the sex was consensual, with all that might mean to the victim.

Plus, there may be concerns about what family and friends will think and say. How will this affect their being on campus, or in the program? And if the coach is popular with other athletes, what kind of retaliation might the victim suffer from those who haven't been abused? And if the administration doesn't seem to care--which is alleged to be the case here--what would coming forward accomplish anyway, aside from ruining the victim's academic career?

Nineteen and twenty years old isn't that old, really. Could be this was the first time the victim had ever been away from home and in "the real world." At that age I was still finding my way through life, naive, and far more vulnerable than I might be today.

Then too, the perpetrator might actually have threatened the victim, or his family. "Tell anyone and I'll kill you" or "tell anyone and I'll ruin you forever," will work with lots of people, especially if the perpetrator is a person in authority, or popular, or both.

And as I say, once the pattern is established, it becomes more and more difficult for the victim to extradite themselves from the abuse.

Similarly, people often ask: why do battered spouses stay, despite repeated abuse over years? The dynamic is often similar.

Each situation is unique, but there are patterns we can discern, and some of those may well have been at work here.