If the entirety of a friendship was founded upon purity, selflessness, and singularly good intention, the relationship would be perpetuated into a realm of perfection casting no shadow of envy, self-gain, or manipulation.
The application of effort alone is not sufficient for the establishment of said perfection; humanity is flawed and thus every effort is inherently imperfect, yet the idealism and perfection is always the destination for wistful thinking and hard progress. The yearning was not introduced by the temporal, but was exemplified by Jesus Christ- the only perfect being to have walked the earth- thus, he loved perfectly and fostered perfect friendships, with perfect desires and perfect intentions.
John 15: 14 Ye are my friends, if ye do whatsoever I command you. 15 Henceforth I call you not servants; for the servant knoweth not what his lord doeth: but I have called you friends; for all things that I have heard of my Father I have made known unto you.
The servant might despise the master and yet still faithfully and obediently serve Him, but what happiness is to be found in such service? When we accept Christ’s extended friendship we serve because we love Him, we have the desire to please Him and he does not withhold the solid unchangeable embrace of His love for us; no longer are we the unwilling servant that knows little of the Master, but an acknowledged friend with the opportunity to learn more of Him everyday- we simply have to choose it and pursue it. He has already invited us.