Some people are just not a good match no matter how you try to stand in their shoes and understand them. For me you're wasting allot of energy on someone who is simply not invested in you. The reasons are his own and nothing you have to answer to or give consideration any longer. Life is short as it is. Spend it with people who want to be in your company and let this fella live his life in whatever capacity he chooses. When you have situations where you might share space with him for get togethers in the family, just be polite and move on.