You are longing for love and appreciation. Your friend is giving you what you need; naturally you will feel attached to him and on long run, will be emotionally dependent on him. If you want him to continue then avoid sexual relations with him. It has been seen that in such relations once sexual desire is fulfilled, most of the male will start loosing interest. Even in absence of sexual encounters, he may start running away from you but at least he will stay longer. Be prepared to accept that any time he may leave and enjoy the relations. However, when chance permits please clarify with him that there would be no sexual relations between two of us.