I would have to say 2 and a half years ... ish, is the longest. I went through schools and college with very few friends, which were from a close bunch. Since college though, that sense of connection with people has dissolved and I don't consider myself to have any friends per say. I have people I am in regular contact with, but I don't know them, and only encounter them through volunteer work.
In truth, I have never felt as free as I do now; no more phone calls or texts at random times and nobody "dropping by" whenever they feel like it. I do, however, sometimes wonder if I'd benefit from a companion, because I think I do have a great deal of affection, it's just, it's hard for me to ... express it. Ultimately, in a perfect world, I would find complete happiness in having but one person to be with, and that person would be the same - a kind of intellectual relation that is mutually beneficial. It brings to mind a very odd article I read on wikipedia about "rational love" - https://en.wikipedia.org/wiki/Rational_love