Lily keeps biting Rafferty please help!

I have had Rafferty for 4 yrs and recently got him a female companion (Lily) who is 3 (from Fat Fluffs rescue). They are both spayed/neutered. The bonding went really well and they got on straight away. It was like they'd always been together.
They were both kept in the same (new) hutch for a week, as advised, and then were introduced to the garden in a run (which Rafferty always goes in). They were fine in the run for another week. Then I let them loose in the garden for an hour together. That night they started fighting and this continued to get worse as the week went on even though they hadn't been outside again, so we had to separate them as it looked like they were going to kill each other as the fights got more vicious. This was more Rafferty initiating this and we think it's because the garden has always been just 'his' (and our dog's).
We took them to one of the people at Fat Fluffs rabbit rescue (in the same cage during the journey) and they were fine there. That night we brought them back and kept them in a small neutral enclosure for 48 hrs as advised.
They were getting on ok, no major fights but a few scuffles, mainly initiated by Lily, the female. She's been pulling tufts of his fur out, though it is coming out a bit easier as he's moulting, but he does have big bald patches now. They were laying together though and licking each other.
Today we put them back into their hutch which we have moved again into a neutral area. It was all disinfected etc. Lily has gradually got more aggressive through the day towards Rafferty, causing him to be very nervous when she's behind him, as it's always his bum she goes for. He runs off and hides in his toilet, where he's just been sitting for most the time cos she can't reach his bum there.
He was licking her head earlier then put his head down for her to do the same but she turned around and bit his bum again and he ran off and hid in his toilet again. They're not fights like before, it's just Lily biting furiously at his bum.
It's really stressing us and Rafferty out. He's not being aggressive towards her. What can we do?
Please help I don't know what to do and I want them to stay together as it seems he does really like her. When they were getting on they were great together. I don't know what's got into her.
Any advice would be very much appreciated!!
thanks

would it be worth giving Chloe [from Fat Fluffs] a call and telling her how upset you and Rafferty are becoming?
Best of Luck

Thanks for the reply. Abi from Fat Fluffs is being really helpful with it all; I thought I'd ask on here to a wider audience as well though to see if anyone's had the same problems and could offer any more tips or if anyone's got any success stories that started off the same as mine!

Hello,

Don't know if this will be helpful.

This has happened a few times recently with rabbits I have bonded. The buns have returned here for a spell in what I call 'boot camp'. Basically I separate them and hardly pay them any attention apart from feeding/cleaning out for 3 or 4 days.

After that I have re bonded them, kept them here for up to a week. Each pair has returned home and remained rebonded.

I think some rabbits get into a habit of attacking. And each one has a go first, to try and get an attack in before the other one.

So, their time separate/right next to each other means they get used to each others body language without being bitten.

If you are able it may be an idea to put them in indoor cages right next to each other, obviously letting them have exercise next to each other for a few days.

Then ask Abi if you can take them back there and try to rebond them on neutral territory again.

Good luck.

Alice