Welcome to BB Honna! Double the rabbits, double the rabbit love, but also, double the work sometimes.
There are some items that’s helpful to know in these scenarios.
1) Are both rabbits in the same cage?
2) Have either been spayed or neutered? If so, how long?
3) How long have they been together, if they are housed together?
4) How do they interact with each other? (I.e. chasing, humping, grooming, etc.)
My initial thought is Boi is ripping out Daisy’s fur because they are no longer getting along. Young rabbits will get along, but as they age, their hormones kick in, and a loving relationship between two, unfixed rabbits is no longer as possible. I advise separating them and seeing if you still see fur, or dedicate the time to observe them together and see if this seems possible.
Is Daisy currently molting? How often do you groom her?
There are a few possibilities. I don’t think any involve a vet, but intervening your rabbits’ companionship will most likely be required. Rabbits do not understand family or companionship once their hormones kick in. It seems like both are at an age where it’s time for those hormones to emerge, so separation until they’re both fixed may be required so they do not harm each other.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.