It is very unusual for both parties to agree on why a marriage broke down and there is often a dispute over the allegations of unreasonable behaviour.
One option, if you receive a Divorce Petition with allegations which you believe to be untrue, is to defend the divorce.
However you need to think very carefully before defending proceedings. If you defend a divorce you will need to prepare (or ask a Solicitor to prepare) an Answer and possibly a Cross Petition. There is a Court fee when this is filed at Court. There are also strict time limits for filing these documents.
Once filed the other party may file a response to your answer and if it appears that there is still no agreement then the Court will list this for a hearing (or possibly more than one) to decide whether or not the divorce should be granted. If you have filed a Cross Petition then the Judge can also decide whether the divorce should go ahead on the basis of your Petition or on your partner's Petition.
All of this inevitably causes more stress and expense.
You should also be aware that if you are simply asking the Court to deem that the divorce will not be granted then this is very difficult to do. Judges tend to take a view that if one person believes that the marriage has broken down then it has!
If you would rather avoid all of this but are still unhappy with the allegations then an option is to ask the other party (or their Solicitors) to amend the particulars. You can then agree what should and what should not be included. If the other party is represented by a Solicitor then they should have sent a draft Petition to you before it is filed at Court and then the allegations can be agreed beforehand.
Another option is to complete the form you will receive with the Petition (the Acknowledgement of Service Form) and confirm that you do not intend to defend the proceedings but that you do not accept the allegations included in the Petition. This highlights to the Judge that you are not admitting to this behaviour. This may be important later if there are proceedings to do with children and the other party tries to rely on allegations made in the Petition.
It is very rare for behaviour allegations to affect any financial settlement so this is not something you should be too concerned about.
Please also remember that the Petition is not a public document and so it should not be seen by anyone other then both parties, their legal representatives and the Court.