Since California is a community property state, the law considers all of the property you and your future spouse own as part of the marital estate in a divorce. Should your marriage not last for any reason, the court will begin the property division portion of your proceedings with the assumption that you both own everything jointly. If you and your intended spouse want to change that assumption, you may want to consider a prenuptial agreement.
In such an agreement, you can each identify the separate property you bring to the marriage that you would want to take with you in a divorce. You can also identify what property would be part of the marital estate and subject to community property laws. This could help eliminate timely and costly arguments in the event of a divorce since the majority, if not all, of your property will already be divided.
Any business interests either of you have could be identified and separated from other assets. How you and your future spouse carve out the business is up to the two of you. Often, parties will exchange assets in order to maintain a sense of fairness and equity when it comes to the agreement. You may also want to address how to handle separate debts one or both of you bring to the marriage.
You may include other issues in your prenuptial agreement as well. This is your opportunity to discuss and make some agreements regarding what your financial life will look life during the marriage. Then if for some reason your marriage ends, you should not have to spend time in court dealing with property division. In order to remain valid, these agreements need to be executed in accordance with California law, so it may be beneficial to consult with an attorney who can ensure your rights are protected and that the agreement conforms to those legal requirements.