There is just one ground for a divorce in Australia. It is that the marriage has broken down irretrievably. The court must be satisfied that the husband and wife have lived separately for a continuous period of 12 months and are unlikely to resume cohabitation. The reasons for separation are irrelevant. The law is concerned only with the fact of separation, not its cause.
Separation is a legal term which means break-down of a marriage.
It is not the same thing as physical separation. The parties may have separated even if they have continued to live in the same house. In order to grant a divorce where the parties are still living in the same house, the Court will require evidence, from a person other than the husband or the wife, that the marriage has ceased to be a marriage in any meaningful sense, both in the eyes of the parties to it and the eyes of the public. In deciding whether the parties have been separated, the court will look at evidence of the parties' intentions, their actions and what they communicated to each other about their intentions. This evidence will show whether there has been a break-down of the marriage.