If you just listen to the song casually, it almost sounds like a breakup song. But if you listen carefully "I should have spoke out" "I didn't know cause we were young" He's saying he should have seen that something was really wrong there but he didn't because he had no life experience. She's definately being abused, whether by parents, a guy, or someone else. The line "don't waste your whole life trying to get back what was taken away" definately hints at rape. Nothing's really "taken away" with other abuse. It says "a moment in time" which shows that this is something that happened once. This song is about a girl he knew who got raped and he wishes he would have done something about it back then. Whether or not "Kristy" is someone he really knew, or this is just an example, it's a lesson to all of us.