Bell frogs!

[belladolittle]

Hi, i recently joined to have some help with my bell frogs.My 5 bell frogs have recently started mating season and a male has become aggresive towards a femal frog.He bit onto her belly and pulled her around the tank calling the mating call and so i pulled the 2 apart and put the female in another tank as her skin has come of one leg.(i feed then reguarly and they have plenty) Is this normal???? Help plz