One of my closest homegirls had a "best friend" and after maybe six months, I could just tell it was more to it...and she ended up being in love with him, on some long term "didn't see it coming" type shit. She was one of his friend's girlfriend back in HS, but her and the BFF became way closer.

She finally made her move with him a few years ago, and he basically friend zoned her...most they ever did was cuddled and he rubbed her titties, but never even kissed. At this point, she has a BF and she's finally over it now.