There are several synonyms for the phrase "too bad" that can be used to express disappointment in a situation. One alternative is "unfortunate," which can convey a sense of sympathy for someone who has experienced a negative outcome or circumstance. Another option is "regrettable," which emphasizes the sense of disappointment or sorrow for a situation that cannot be changed. "Disappointing" is a similar term that can be used to convey a feeling of frustration or sadness. Finally, "heartbreaking" is a strong synonym that conveys a deep sense of sadness or grief at a negative event or outcome. Using these synonyms can help to convey a more nuanced and empathetic viewpoint in expressing disappointment.