Are we supposed to believe that Harry and Sally were once satisfied with friendship, or that they always harbored romantic feelings? Option 2 seems more likely: Their friendship was actually a courtship all along. Like Harry and Sally's friends, the viewer expects and wants the couple to get together. And even first-time viewers with the most basic understanding of plotting must realize that, narratively, romance is inevitable.
The upshot is that truly platonic cross-sex friendships appear to be easier in real life than in Hollywood movies. Link
It is much easier for women to answer the "just friends" question with "yes" because of the process through which females search for a mate, which is much more rigorous than that of males.
For men, on the other hand, giving the answer is a bit more difficult. Even if we mentally reject a woman as a potential sexual partner (which happens rarely) due to circumstances like already having a girlfriend, the unparticular attractiveness of the women or other reasons I can't think of now because I just woke up and hadn't had my coffee yet, there is always the chance that circumstances might change and the female friend to be thrown into the pool of women we want to have sex with.
If this sounds sick to you ladies, don't blame us men, blame evolution. Or God. It depends on your personal beliefs (or political orientation).
And I agree with Dev totally.
I think some women who believe they are "just friends" with guys would be surprised at the reaction if they initatied a sexual relationship.
I've also got female friends toward whom I have both friendly feelings and sexual attraction, but I keep the attraction to myself for one reason or another (one of us is in a relationship, she's not into guys, she's made it clear that she's not interested, etc.). I think that's more common, but true platonic friendship is absolutely possible.
Ok, so those female friends that you have no romantic feelings for, are you sure they feel the same way? If not, then it's not completely platonic.
I dunno, maybe my definition of friend is more intimate. I have a large group of acquaintances that I would, for example, invite to a large party, or invite out with a group and yes, there are females there that I can say I don't have romantic feelings for but I don't call them friends in my mind although I might say, "yes" if someone asked if they were my friend.
Friends are people I'm excited to hang out with even one on one and that make me laugh and that I have fun with. I can't see how I wouldn't be romantically attracted to those women. I just don't understand how could anyone not be?
In other words, yes, I'm talking about a good, close friend. Such friendships are rare between genders, but heck, they're rare within one gender too.