In short
Whose name is on the lease?
When asking who may stay in the rental home, the first thing looked at is the lease. Who signed the rental agreement, and are both of you on it or only one? That starting point determines a lot, but it is not the whole story.
If you are married, the family home is a specially protected place. Even if the lease is in the name of only one partner, the other partner also has rights to that home during the marriage. In a divorce, the justice of the peace can decide who may stay there temporarily, regardless of whose signature is on the contract.
If you are legally or de facto cohabiting, the name on the lease carries much more weight. If the lease is in your partner's name and not yours, you have no automatic right to stay. If both of you are on it, you are jointly responsible and must agree on who leaves and who stays.

