You will need to do a proper reintroduction. So put them in an area they’ve both not been. Just a pile of hay (and veg at usual feeding time) in the bonding area. No hides. You then need to thoroughly clean the cage they’ll be in, new bedding and rearrange it.
It’s not usually suggested that you separate on medical grounds. Sometimes it can be stressful for them. It can sometimes also lead to a break in their bond.
Good luck with the bonding and let us know how they get on
Hopefully they’ll get on like they used to before.
Bonding and Interaction: Illustrated social behaviours and bonding dynami