It is a fact of life that most of us have friends that are women. Some of these female friends we may find attractive. However that shouldn't affect your relationship as friends. Its a vague and [if you let it be] causally impotent attraction, like you'd have for any other cool, attractive woman, and nothing more. It doesnt need to, and shouldn't be, made into anything more i.e some weird and unnecessarily complicating notion of being in the 'friendzone'.

Fuck that, you're mates with this girl and thats cool as it is, but leave open the possibility of more. You do this by not mentioning/thinking about the 'friendzone', carrying on with your own shit, pursue and enjoy time with other women, and generally try and have a sweet life. Theres a high chance that in this relaxed and amiable atmosphere your female friend may become just attracted to you as you mildly and vaguely are to her.

Twice in the last week ive been out for drinks etc with women I simply saw as friends and its ended in something passionate and amorous each time. Completely unexpected as well as i'd been going about it with zero expectation or pursuit of something sexual happening.

TL;DR chill out and enjoy female company. pursue your own path in life, keep a relaxed and open to any possibility stance, and theres a strong chance it'll move from friendship to something amorous. All without any bullshit categorisations and the accompanying stress of the nonsensical notion of the 'friendzone'