WHY ISNT THE OTHER PERSON BEING CHARGED?

I recently was aulted and retaliated in self defence. I went to report the incident at the police station and got arrested myself and am now on bail pending ault charges. The person who aulted me has already been charged with harrment of me but the police have said they cant be arrested until my case is dealt with. WHY??? It seems so unfair, i have injuries the other person has none.