Friendship is like maintaining a plant. Sometimes you may forget to water it, but if enough thought and care goes in overall, it will still thrive. However, one's choice of people should be considered carefully in relation to the reality of the life one leads. Just like a plant that needs full sun can't be planted in shade etc. Once I was honest with myself about which people I couldn't support a friendship with, due to differences in expectations or values, I stopped making friends I couldn't keep. I was a fair age before I figured it out. In my experience, the lasting and deep connections are few, but they are enough.