Prenuptial agreement
When two people get married, there is question of legal community property and their possessions are merged as one. Each partner is entitled to half of it. Not only the possessions become community property, but the debts as well, for that matter. The debts either partner enters into can be recovered from the community of property.
If this is not your intention, you have to make a prenuptial agreement.
Prenuptial agreements can be made by future spouses before the marriage is concluded as well as by spouses during the marriage. A prenuptial agreement has to be concluded by notarial deed, subject to being declared void.