Quail pair problem

So I have a roo and a hen and everything was fine until one day my hen decided she'll stay being very very mean. She was the size of my roo when I got her now she's much bigger because she eats all the food and leaves very little for him, he acts as if he does not want to eat if she's not there and trends to leave her the food. On top of that she pecks the roo, constantly tearing out his feathers, he does not fight back just run away a bit only to be followed and pecked again. I've heard of quail just snapping and going permanently crazy for no reason and I'm afraid that might have happened to her. I don't want my roo constantly hurt and deprived of food. I seperated them with a see through sheet so he'd heal, they constantly saw each other just couldn't touch. I've put them back together for a bit today to see what'll happen and after literally 2 minutes she started pecking him violently going crazy at him. I was thinking of selling her and getting my roo a new hen. They don't 'bond for life' as far as I'm concerned do they ? Will it be ok if I do that ? I don't want my roo constantly hurt and having them seperated constantly gives them little space.

What kind of quail? Quail that mate in pairs do tend to be monagamous and will spend their whole life with the same mate.

They are button quail

Button quail are monagamou and mate for life, just like doves. You could replace her mate but whichever bird was left without a mate would likely waste away and die. There is something wrong in their environment and likely theyll return to normal once its fixed.

Check you hen over for wounds. If she has any sores on her back or feet she will become aggressive to the roo.

Have you changed what they see or hear from their cage since this behavior began? Sometimes turning the cage so they cant see the tv or whatever else in the room moves a lot or makes noise.

Worse case you can separate them for a couple weeks but keep them caged side by side and then re introduce them and see if that will stop it. Another option is moving them to a new cage they have never been in. It sometimes makes them insecure enough that theyll stop squabbling.

dc's comments are right on but I would like to stress that the diet must be high protein and feather plucking and eating is a sign of low protein or calcium. You should have them on game bird crumbles and no more then 50% good quality finch seeds mixed in, offering fresh veggie or fruit daily or at minimum 2 times a week. I give mine hard boiled egg smashed with the shell several times a week even cooking the hens eggs and feeding them back to the adults. Also they need a dish of ground oyster shell or egg shell for additional calcium. Can you post a photo of the pair? I wonder if you have 2 of one sex?