Whether desirable or not all friendships have an expiration date. The ebb and flow of life causes people to change over time. Commonalities fade and disappear whether the memory of them remains or fades as well. The connections that brought you together are severed, and may no longer be present. Where once your lives were in harmony, now there is only noise.
People drift in the river of life and absorb new experiences. They are altered by these experiences. Where once your commonalities drew you together, now they have been replaced and no longer mesh. That person you imagined in your mind exists only in your mind. The body that contained that person exists, but the person inside does not. They have changed and appear alien, unknown, just another stranger.
There comes a time when one must accept that the friendship is no longer possible. Not only that, but also that the changes that have occurred are not amenable to establishing any renewal to that friendship. The sad day comes when efforts to reach out are ended. Two people who used to mean so much, whose lives were intertwined, now go their separate ways. Even brothers often come to this point.