Be completely honest with the other person and yourself.
Be quite sure that you are not giving the person reason to be jealous and paranoid, or that you are not exploiting his need for you. However, if you are being accused unfairly, stand your ground as long as you are not jeopardizing your safety. Do not break off contact with your family and friends in a vain attempt to convince the other person that you only need him.
Listen to the person and encourage him to be open.
If he was abandoned as a child, he may find it painful to talk about, but avoiding the issue may be compounding the problem. If his abandonment issues are deep-seated, though, it is unlikely that just talking about it will change his behavior. He is likely to need professional help.
Encourage the person to recognize that his behavior is destructive and can actually cause the very thing he fears most.
Gently help him to recognize that he probably needs counseling to change his responses. Also be aware that beliefs and learned responses are notoriously difficult to change, especially without professional help.
- Avoid colluding someone with abandonment issues. This is quite easy to do in this situation. Do not repeatedly reassure him, especially if this seems to make no difference in his beliefs or behavior.