fighting fish

Hello all, I was wondering I have a pair of yellow labs and have had them for about 6 months now. They have produced many many fry together but all of a sudden the male keeps messing with the female harshly. Her tail looks like **** and she spends most of her time trying to keep away from the male. While all the while shes holding. I dont understand whats going on this is new, any suggestions would be great. Thanks!!!!!!