In England and Wales the only ground upon which a divorce can be sought is that the marriage has broken down irretrievably and this can be evidenced by one of five facts.
The Office for National Statistics (ONS) has published statistics which show that the most common reason people have cited when seeking a divorce is:
"that the respondent has behaved in such a way that the petitioner cannot reasonably be expected to live with the respondent".
This is a subjective test in that the divorce petition will need to set out examples of the respondent's behaviour that the petitioner consider to be unreasonable. However, the content of the petition must satisfy a judge that the petitioner is entitled to a divorce.
To avoid the need to "blame" the other party a divorce can be obtained on the basis of two years separation with consent. However, many people do not want to wait if they are satisfied that their marriage has broken down irretrievably. In many cases both parties agree to divorce. All political parties appear to be agreed to progress divorce reform and a "no fault" divorce bill was passing through Parliament when it was prorogued earlier this year. We wait to see if the introduce of "no fault" divorce will arrive in 2020 which I expect would see a reduction in the number of people divorcing on the basis of the other parties' behaviour.
Unreasonable behaviour - which can include infidelity - was cited as the most common reason in all divorces last year.