I was hoping for a response but am hoping that things did not escalate. Your male is maturing into an adult. Given he is a strong willed breed and a young male he would feel he is the better choice to be boss. The boss dogs gets what ever he wants regardless of whether it is hers or not. Given she is older and likely the boss when he was maturing, she isn't as willing to just give up her treats. He can't let her get away with disrespecting him and you are right to be concerned. The size difference could lead to him seriously injuring her even if the didn't mean to.
You will need to have your boy obedience trained. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
This will allow you to control him with commands and have him see you as the boss. If you are the boss, you control who gets what and you won't be allowing him to intimidate her. You can also get him a basket style muzzle to wear when they are out together and you are not able to watch them closely. This will at least prevent him from biting her. I would separate them when you are not home to prevent injury while you are gone.
Neutering may reduce his dominance a little but he'll still feel like he is a better choice than her for the top dog due to his size and nature. I would always separate them when giving treats until you have absolute control over him. You should do the obedience training anyway since large strong willed dogs need the training to be controlled adequately.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.