No. A divorce is not automatic. In order to get a divorce you first have to file a request with the court – a Petition for Dissolution (divorce). The earliest date you can be divorced in California is six months from the date the Petition and other papers are served on your spouse. Service can be accomplished is many ways, including having a person over 18 years of age, other than you, handing the papers to your spouse; service by a registered process server or the Sheriff; or by your spouse signing paperwork that is mailed to him/her. Once service has occurred, then the six month waiting period starts. If you want to be in divorced in a particular year, you have to file and serve papers on your spouse no later than June 30.
If the other issues of the divorce (i.e. property division, support and parenting issues) are not resolved within this six month time frame, you are entitled to request a “bifurcated Judgment.” This is a technical term meaning that your status as a married person is separated from the other issues in your case, and a judgment terminating your status as a married person is obtained and the other issues are decided later. That makes you single again. This does not happen automatically. If you want to terminate your marital status before the other issues of your case are resolved, you must either present an agreement to do this or file a motion to ask the court for a bifurcation. The necessary paperwork has to be filed with the court for this to happen whether by agreement or not.
If you and your spouse or partner reach an agreement about all of the issues in your divorce within the 6 months, then you can submit the agreement and the other required paperwork to the court for the divorce to become official and you will become single when the six month waiting period has elapsed.
All methods of becoming divorced require some affirmative action on your part and a court order that says you are divorced.