If tenant arrested for assault, what happens to the remaining tenant?

I have a couple who are 2 months into a 6 month rent. Last weekend there was a disturbance where people were running in and out of the building at 2am (they’re on the 2nd floor), the whole block of 6 flats was woken up and concerned and one neighbour phoned me at 2am. There was yelling from the driveway up to the flat and back. Glass items were thrown from the 2nd floor and smashed onto the driveway.
The next morning they both disappeared and one of their neighbours swept and hosed down the driveway.
Last night she started yelling and tried to pull him out of a car (on the property) by his legs and was punching him. The police arrested her for assault. Im told that when she drinks she behaves like this.
Inside the flat there is a hole in the wall where she threw a bottle and there are also blood splatters on the wall.
He is getting a restraining order against her and the police said that when she is released in the morning, she is entitled to return to the flat until the restraining order is applied. He wants to remain as a tenant but he wants her out.
If I give notice do I have to serve it to both of them? I have to give 2 months notice.
In light of the damage and disruption, can I serve immediate notice on her alone? She has family she can live with nearby
If she is served notice to leave immediately, can she still be liable for half the rent until the end of the tenancy? He doesnt think he will be able to afford all the rent on his own
Any advice is greatly appreciated, thank you

Who’s names(s) are on the contract?

Both of them are named on the contract

They are both in the fixed term and only two months in
They can both surrender and you can accept or you would need to serve a section 8 ( but you are only two months in )
These are mitigating circumstances as there is violence involved so you are likely get an exception to four month notice if you have to serve a section 8.
I would advise you to take legal advice.
If you are a member of the NRLA they will give you free advice or call a specialist solicitor eg Anthony Gold or David Smith at JMW

Thank you for your advice