The man who is without love is narcissistic, he is closed. He knows only himself. And how much can he know himself if he has not known the other, because only the other can function as a mirror?
You will never know yourself without knowing the other. Love is very fundamental for self-knowledge too. The person who has not known the other in deep love, in intense passion, in utter ecstasy, will not be able to know who he is, because he will not have the mirror to see his own reflection.
Relationship is a mirror, and the purer the love is, the higher the love is, the better the mirror, the cleaner the mirror. But the higher love needs that you should be open. The higher love needs you to be vulnerable. You have to drop your armor; that is painful. You have not to be constantly on guard.