Can someone explain a few things to me?

Rebecca's father abandoned his family. It seems he was unhappy, packed his bags one day, and just left.

Rebecca stopped speaking when she realizes what has happened--that her father has started a new family and simply abandoned his old one. She was visiting a college and just happens to see her father and his new wife and baby. She says in the movie, "I didn't know how to tell my mother." Hence her not speaking was her way of keeping the secret that she knew where her father was.

Thanks for this.