Antonyms for the phrase "comes on to" could be "backs away from" or "rejects." While "comes on to" suggests a forward, flirtatious or aggressive behavior, "backs away from" suggests the opposite - a cautious, perhaps shy, or even uninterested response. Similarly, "rejects" implies a negative reaction to an advance or flirtation, rather than accepting it. These antonyms reflect a different communication style, one that is more reserved, respectful or assertive. It is important to always pay attention to and respect other people's comfort levels in social interactions.