It sounds like they are re-establishing their dominance, and it honestly sounds like the bond may already be broken. Were either of them injured in the fight (any broken skin)?
For now, I would keep them separate all the time, but do pre-binding, as I think starting over with bonding sessions in a neutral space are in order. Hopefully they will patch things up quickly. Also, sometimes rabbits will try to re-establish dominance when one of the bunnies is ill.
A vet visit would be good to rule out any underlying illness that could have triggered this.
If one of the bunnies was hurt in the fight, then you should probably take a 1-3 month break to allow them to cool off. But, it doesn’t sound like things got that serious with the fight??
Also, to clear my confusion, was Poppy spayed when you first bonded them in October? It sounds like, no, but then was spayed later in November? It can take females up to 6 months to drain hormones, so all of this could be due to her hormones changing over time.
If that’s the case, I would separate them for a 2-3 months but keep up pre-bonding, then start bonding again. Hopefully things will go smoothly once they have time to cool off.
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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.