She needs to be desexed, it is only very rare cases where a neutered male and intact female can have a successful bond. Sometimes the hormones of the female can still lead to mating behaviour from the male even though he’s neutered, but usually the female is territorial and defensive, and can be very bossy.

For now, keep them separated, there’s no point or help in letting them get more stressed out by having them spend more time together. Keep them in separate cages, have them out for separate play time, but continue with pre-bonding things such as swapping toys, blankets, litter trays and cages etc.

Once she is spayed, you will need to continue to keep her apart from him for at least 6 weeks, potentially even more depending on how her hormones are. Some females show no sign of being hormonal after 4 weeks, but I do know of one female who was extremely hormonal after her spay for another 6 months. The extra time spent apart will also help them to forget their differences. Trying to introduce two rabbits that have recently been fighting is only a recipe for disaster, and you need to let them rest for a while so that they get over it and can somewhat reset their introduction.

When you do reintroduce them, do so in a new neutral area, and keep the time really short. 10 minutes is much too long for first introductions, 1 minute is plenty of time and you can even restrict their movement by petting them the whole time and making the whole thing a positive experience. Over time as things progress you can slowly increase the time frame, but with a fighting history, I think it’s best to start really slow to ensure that you completely avoid any further fighting which will only set them back.

It would be okay to have their pens side by side as long as they can’t reach each other to bite through the bars. If they seem content living side by side, that is. This would maybe stress out some bunnies. Being neighbors may help the bonding process later.