I think it is pretty common that children who lost a parent or had some other traumas in their childhood have issues of rejection, abandonment, need for extra support and the like. Some people don't have this experience and are exploiters by nature.

I think it comes down to deciding whether you want to keep him as a friend because he causes you undue distress. The mature thing to do is to tell him how you feel in a gentle way. I'm just saying because you asked. Yes, this will probably hurt him but so will ignoring him. I think the only way to stop your distress is to tell him how you feel. He may not know what he is doing and he may appreciate it. You never really know what another person is thinking. I think we assume too much when it comes to issues with friends. Being up front, if it is a true friend, is always the best route in my humble opinion.

Best wishes