I received this question from a new client this month, and had several email inquiries along the same lines. The short answer: if one of you wants a divorce, then the court will grant the divorce. The slightly longer answer: if only one of you wants a divorce, the other person can make the process take longer, and potentially cost more than necessary, but ultimately that person can not stop the divorce from being granted.
California family law does not require that both parties agree to the divorce, simply that one spouse decide that the relationship is irretrievably broken and that he or she wants to divorce. No specific reason needs to be given for the divorce. (Clients often think that they need to gather evidence of infidelity, etc. to bolster why they want a divorce.) In fact, the Petition, used to start a divorce, has only two checkboxes re: reasons for divorce: (1) irreconcilable differences, and (2) incurable insanity. (When I explain this to clients, I can’t tell you how many ask if they can check both!)
If you are in a situation where only one of you wants to divorce, be clear about your intentions, both to spare each other emotional distress and to minimize potential legal battles later on. For example, if you are in counseling together, is it to repair your relationship, or is it to learn how to successfully co-parent? Of course, if you find yourself (or a friend) in this situation, a consultation with a family law attorney can be helpful to understand your rights and responsibilities, as well as to strategize and understand the process.