Friendship is a peculiar thing. Because it is one of only two deliberate human relationships, it is prey to the same exacting and frequently unsatisfiable demands which refine and intesify themselves in all other parts of life. Think of the insatiatiability characteristic of the rich and famous. The search for satisfaction leads to Leno's acre of cars, Hollywood collections of husbands and wives, and gourmands dissatisfied with a $500 dollar meal and $1500 dollar wine.
The desire for the "perfect" this or that was built into us to make us good, but mixes with our selfishness to dissipate our gratitude and contentment (see Buddha's 4 Noble Truths). This ever greater and more refined sense of our preferences has an impact on the possibility of finding a true companion. For me, a companion moves effortlessly with you to the essence of your concern that moment, and then moves deeply and rapidly beyond. You quickly become of one mind, and then swim together like fish in the sea.