I think the friendzone does exist but there comes a point where its a land of no return if the line is crossed. The line can be crossed in a favorable way but going from JUST friends to hooking up back to just friends - eh. too much transpired. Someone WILL inevitably have issues about the situation. That's just how I've experienced it. I think there are definite plus's to being in the friendzone 1st and upgrading to together status but there are also downfalls. Sometimes those platonic friends share more and use a little less discretion than you might with a potential lover in the early stages of socializing. Not that you shouldn't be frank and candid with a long term partner candidate, but sharing details about your sexual past for instance. I might not share ALL the gory details with a serious long term partner that I might with a platonic friend. There are certain details I could most definitely live without knowing about in a gf that I wouldn't care about knowing in a friend.

But yeah, I've had a handful of great female friends where we were both in each other's 'friendzone'. I think there are definitely multiple types of friendzones however. Voluntary and involuntary. Voluntary falls between the friends who are like a sister to you, who you grew up with, the ones that aren't the cutest but you're still great friends with etc. Then the involuntary ones are where you're either not ready for commitment and you know it'd fuck things up straying over the line or where the chick is issue ridden or loose and you know it'd be entering a world of trouble going there. But I've also been in someone else's friendzone and managed to break free of it to have a long relationship out of it. I think some friendzones aren't necessarily intentional, sometimes people just aren't ready and that's probably better in the long run.