Hi,
It can take a pair a while to bond, and not all birds are compatible. They choose their mates in the wild and do not always like the mate we choose for them. If these birds are not at least 2 years old, this is part of the problem. They are too young to be together and need to be separated until they are 2 years old. If they are over 2, then they may need more time, or they may not bond at all. If the male is actually biting the female, and not just snapping at her, then you need to separate them for now. Put them in cages, side by side, and wait and see if they start showing an interest in each other. If they start sitting close to each other and interact through the cages, then try putting them back together. There is nothing you can do to make them get along. If they fail to bond, then you need to try different mates for each bird.
Thank you for asking Lafeber,
Brenda