Looking for synonyms for "running out on"? Here are a few options to consider. "Abandoning" suggests leaving someone or something behind without intention of returning. "Fleeing" implies a sudden departure, often in a state of panic or fear. "Ditching" is a more informal term that suggests leaving abruptly or intentionally without warning. "Deserting" implies a more long-term or permanent abandonment of someone or something. "Betraying" suggests a breach of trust or acknowledgement of responsibility. Consider the context and connotations of each option to choose the best synonym for the situation at hand.