A "no fault" divorce proceeding does not require one spouse to prove that the other spouse committed a wrongdoing. For example, a wrongdoing could be considered one spouse having an extra-marital affair or secretly incurring debt that the other spouse did not agree to.
California is a "no fault" divorce state, which means that either party can get a divorce simply for "irreconcilable differences", which means that you cannot peacefully coexist and live with your spouse any longer.
Another aspect of "no fault" divorces is that one party cannot be financially penalized for extramarital activities. Therefore, if your spouse cheats on you, you could still be legally required to pay spousal support to your partner and give them half of your assets, depending on your situation.