If you have committed a crime, irrespective of the circumstances or any regrets you may have the CPS will only consider two things. Was a crime committed and is it in the public interest to pursue the case? Because of the gun culture prevalent today, the CPS may decide to continue because an imitation firearm was involved. Were I in your or your partner�s position, I would consider, for yourself, why did I do this? Your partner may equally consider why you did it. I would be more concerned about my relationship with my partner than legal implications. I hope, in all sincerity that the case is dropped, removing that pressure and you and your partner can stay together and live a long and mutually fulfilling life. My best wishes go to you both.
Disclaimer- I am not legally trained and any advice, actual or implied is acted upon purely at your own risk. I accept no responsibility for consequences resulting thereof. .