The phrase "am gone on" typically means to be fond of or infatuated with someone or something. Some possible antonyms for this expression could include: dislike, detest, repel, reject, or hate. These words suggest a feeling of aversion or distaste rather than attraction or enthusiasm. Other antonyms might include terms like "uninterested", "unimpressed," or "nonchalant," which convey a lack of positive feeling or enthusiasm altogether. Ultimately, the opposite of being "gone on" someone or something is simply to feel indifferent or negative towards it.