There is, in fact, only one 'ground' for divorce in the eyes of the law and that is that a marriage has irretrievably broken down. However, a married person wanting to get divorced (the petitioner) will have to give the reason(s) for the breakdown and give evidence that it is irretrievable.
Known as the 'facts' of divorce (although commonly referred as the 'grounds for divorce'), the reasons that can be given in a 'divorce petition' for the irretrievable breakdown of a marriage are:
2. Unreasonable behaviour
4. Living separately for at least two years
5. Living separately for at least five years
Where adultery is given as a 'fact' or reason for the irretrievably breakdown of a marriage, the petitioner must be able to prove that their spouse (known as the 'respondent') has had sexual intercourse with a member of the opposite sex. Alternatively, the respondent can admit to the adultery. To be regarded as having caused the irretrievable breakdown of the marriage the adultery of the spouse must be so unacceptable to the petitioner that he/she finds it intolerable to continue living with the respondent.
In the case of unreasonable behaviour, the petitioner must convince the court that the respondent has behaved in such a way that the petitioner cannot reasonably be expected to live with him/her. There are many examples of behaviour that taken individually are not very serious but when taken together will be enough to show the court why the petitioner cannot reasonably be expected to live with the respondent.
The fact of desertion can be used in cases where the respondent has left the marital home for at least two years, without the consent of the petitioner or without the respondent having reasonable grounds to leave.
Where spouses have lived apart for more than two years and both agree to get divorced, the fact of living separately for at least two years (by the date the divorce petition is presented to court) can be used in the divorce petition.
In the situation where a married couple have lived apart for more than five years, it is possible for one of the couple to apply for a divorce without the other's consent.