Why does an abused girl push away the nice guy shes attracted to?

because she has trust issues. while she most likely cares for you, she probably has a lot of emotional scars. this can include feelings of worthlessness, like she doesn't deserve you, or that somehow she caused the abuse . she could also fear that you, too, may become an abuser. Its hard to deal with people you love abusing you. these kinds of emotional scars can take years to overcome..if ever.