Hey, Kirsty! Hello and welcome!
As much as we would like to help you, we really need more information from you about your pond and the set up. How “small” is your pond — size, dimensions, depth, gallons....? Do you have a pump and filter? How long have you had the pond? Can you describe the “injury” for us....what does it look like, how long has it been there, how is the fish acting?
In my [limited] experience, I haven’t seen anything that I would call bullying behavior with GF (not that it doesn’t happen), but my first thought was that your fish might be spawning. Males can get quite aggressive and can actually injure the female.
Pictures of the fish might help, as well.