As long as you are lucky, you will have many friends; if cloudy times appear, you will be alone. -Donec eris felix, multos numerabis amicos; tempora si fuerint nubila, solus eris
Your friend is your needs answered. He is your field which you sow with love and reap with thanksgiving. And he is your board and your fireside. For you come to him with your hunger, and you seek him for peace.
If friends disappoint you over and over, that's in large part your own fault. Once someone has shown a tendency to be self-centered, you need to recognize that and take care of yourself; people aren't going to change simply because you want them to.
Genuine human friendship is on the basis of human affection, irrespective of your position. Therefore, the more you show concern about the welfare and rights of others, the more you are a genuine friend. The more you remain open and sincere, then ultimately more benefits will come to you. If you forget or do not bother about others, then eventually you will lose your own benefit.
I don't think life offers any greater experience than the joyful sense of recognition when one finds in a new acquaintance a real friend, or when an old relationship deepens into friendship, or when one finds an old friendship intact despite the passage of years and many absences.
Nothing is more limiting than a closed circle of acquaintanceship where every avenue of conversation has been explored and social exchanges are fixed in a known routine.