"Passed rubicon" is an idiomatic expression that means to have crossed a point of no return or to have made a decision that cannot be undone. There are many synonyms that can be used to convey a similar meaning, such as "point of no return," "irrevocable decision," "critical juncture," "moment of truth," "life-changing choice," or "turning point." All of these phrases suggest a significant moment in which a person must make a definitive decision that will have lasting consequences. Once the "rubicon" has been crossed, there is no going back, and one must face the outcome of their choice, be it good or bad.