In that case, it really depends on the kind of qualities that she is looking for in a guy.
If she tends to be more attracted to the very masculine and/or protective type, then the bullying situation may have negatively affected her.
However, she may be more attracted to the studious guy or the artsy guy. If that is what she likes, she may not care all that much that she saw you being bullied.
Again, it just depends on the kind of qualities that she tends to be attracted to or look for in a guy.