After you enter into a domestic partnership, your creditors can reach both your separate and your community property to satisfy any debt that you are found legally liable to pay.
The act of entering into a domestic partnership will not by itself cause the house to be characterized as community property. However, once you enter into a domestic partnership, any contribution by either party to the house (unless you have a "pre-domestic partnership agreement") can create a community interest, to be divided the dissolution of the partnership.
It would be best for you to hire a local family law lawyer to discuss this matter in more detail. You and your partner should discuss a pre-domestic partnership agreement to protect assets.