Sudden aggression between rabbits

[NorthStarAtMyFeet]

I have had a bonded pair of female rabbits for 2 years.
They very occasionally have a scrap but this weekend is on a whole new level. They live in a hutch in a shed but I let them into the garden every day weather permitting.

As soon as they were in the hutch last night they started fighting so I separated them. Today I tried to reintroduce them in the morning - fighting again, so I separated them. This afternoon, same thing.
It seems a long time to hold a rabbitty grudge.
What's the best way forward?

Keep them apart, get them neutured, wait 2weeks and reintroduce them, make sure they have plenty of space and not kept in same hutch because that is not enough space unless its open to a run/inside shed or its at least 6ft long and over 3ft wide

Could one of them be ill? One of our rabbits had a nasty ear infection and it affected her behaviour.