The phrase "bends over backward" means to make a great effort or to go out of one's way to help someone or achieve something. Antonyms of this phrase could include "apathetic," "indifferent," or "unconcerned." These words convey a lack of effort or care in a situation. Other antonyms could include "stubborn," "inflexible," or "unyielding." These words suggest an unwillingness to make an effort or to change one's stance. Additionally, "disinterested," "unenthusiastic," or "half-hearted" could also function as antonyms of "bends over backward," indicating a lack of passion or commitment to a cause or person.