Why does Gloria change her name in the novel, Valentine?

On Valentine's Day, after an argument with her mother, Gloria flees the house and spends the evening at Sonic. When Dale Strickland, an attractive young man, invites her to spend the evening with him, Gloria accepts. However, Dale becomes intoxicated, aggressive, and violent. He rapes and beats Gloria. In the morning, she determines never to be called by her given name again, giving herself the name, Glory, instead.