The behavior you've described could be indicative of someone who is somewhat possessive or sensitive about their feelings. They might feel vulnerable about their attraction and could react negatively if they perceive that their feelings are being acknowledged or revealed. This could also be a sign of someone who struggles with expressing their emotions or is uncertain about their feelings.
There isn’t a specific term for this exact behavior, but you might describe them as emotionally insecure or defensive when it comes to their feelings for that person. They might also be exhibiting mixed signals or conflicted feelings about their attraction. Ultimately, it can depend on the individual and the context of the situation.