So he wants to divorce on the grounds of unreasonable behaviour? If that's the case then one person has to file against the other and they are the one who pays the court costs up front.
Or you do a two year separation....or a 5 year non contested separation.
In the scheme of things does it matter what the reasons are?
But...
It was important to me to divorce him on unreasonable behaviour and l had enough examples. It also meant l paid for the Court application.
However.... it doesn't actually mean anything long term. There are no benefits i.e being awarded a better financial split if you divorce him or vice versa.
What you need to decide, is how you want this to go. Is it important to you that you divorce him, therefore you can start that now if you have enough examples
Or, is it important that you keep to the truth that you were still very much a couple, in which case do a 2yr separation.
Take some time and have a think to what is best for you.
I personally did unreasonable behaviour as l had plenty of examples (OW), l wanted it over with asap and my solicitor wanted us financially split asap as he is not financially aware.