O no, thy love though much, is not so great, It is my love that keeps mine eye awake, Mine own true love that doth my rest defeat, To play the watchman ever for thy sake. For thee watch I, whilst thou dost wake elsewhere, From me far off, with others all too near.
Friendship exists outside our modern economy of scarcity... It's not about apportioning vanishing resources of time and energy. Friendship is a blessed relic of the ancient economy of the gift, and the time freely given to people dear to you actually creates magical abundance.
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.