The only straight guys I know that have had "pure" friendships with women were A) Older (and I'm not talking geriatric, just old enough to have started thinking with the larger head); B) In a healthy/happy/committed relationship; C) Not as "Macho" (don't know how to explain this one, I call it having a few extra chick chips, meaning they relate to women well, but it's got nothing to do with being "Gay").
But even the most happily married, comfortably connected to his feminine side guy will have the odd "I wonder what she'd be like in the sack" thought about long time work colleagues or his buddies wives, that's natural. I don't think that's the same as wanting to fuck them. I'd like to believe that men evolving beyond their hormones is the norm, not a rarity.