I guess I'm a little confused by this sentiment, because he isn't my best friend. I mean, we've only been dating for 6 months. I don't even bother giving "long term potential" serious thought myself until a year in. There are plenty of things I've confided in friends, instead of him, because they were insecure/unnecessary things that would have just put stress onto the relationship.
The way I handle the timeline is, the first 6 months are the "honey moon" stage and the following 6 months are when you really get to know the person, and get a sense if you're compatible, or if it was all hormones/first flush. Until I've been able to know that person, I don't necessarily trust or rely on them as much. I've just been trying to take this one easy, and live in the present.