Along the years and the many different types of friendships I've had I can talk about two that really stand out: girlfriends and SOS BFFs. Personally I have both types of these kinds of friends, and I like them both, but I do classify myself in one of those categories.
These are the kind of BFFs you always find reading about in YA books, where the best friend always comes before the boyfriend. Currently I'm reading one right now lol. I find myself in this category, where I like to keep up with my friendships on a weekly basis, either texting, or skyping. I consider friendships a very important bond considering all I've been through and since then I've learned to never let them go or consider them in the palm of my hand.
SOS BFFs are the kind of friends that are close to you and can go without talking to you for months and when they talk to you everything feels the same. No hard feelings, and mostly joy overflowing after months of not seeing each other.
What happens when you mix these two kinds of friendships is chaos. The girlfriend thinks the SOS doesn't care and the SOS thinks the girlfriend is suffocating her. The key to this relationship, as to every other, is to compromise. To compromise, respect and tolerate each other's belief.