I'll admit it. I'm a guy, and when meeting a new woman the thought process goes like this:
1. Is she attractive enough that I'd want to have sex with her?
2. If so, is she also interesting enough that I'd want to be in a relationship with her?
3. Wait, she's talking - better start paying attention and maybe I'll figure out the answer to the previous question...
This is fairly accurate.
Regardless of what previous (or following) posters have said, I refuse to believe that if they have an attractive female friend, that have never wanted to have sex with her.
What people think/want is different from what they'd actually do. Personally, the negative consequences of attempting such an endeavor outweighs any desire I might have. The reasons why I have ended relationships before are the same reasons why I would not pursue a new relationship with someone else: I realize that it would not work out.
There is nothing wrong with finding a friend attractive, but if you understand that that person has an important character trait that is incompatible with your own, that makes it easier to keep things platonic.
For instance, I'm a competitive guy who wants to do my best at sports, even if I lose. It is my belief that you should always try your hardest because showing 'heart' matters to me. It shows that you care, that you did your best to succeed, and that your opponent had to work
hard in order to win. If at the end of the day, you have done your best and still fail, you can still rest well knowing that you gave it your best shot and that your opponent respects you for not being an easy adversary to defeat.
Contrasting this to a girl I knew, who was so uncompetitive that she didn't even want to play boardgames for fear of losing. When she was growing up and trying games/sports, her father would put her down whenever she failed, and it became ingrained into her that if she could not be the absolute best at something, then she might as well not even try. That mindset never made sense to me because, how can one become the best if they never try, or never keep practicing? That defeatist mindset is a deal-breaker for me as that would cause major problems in the relationship, plus that is not an attitude that I would want passed on to my children.
In another instance, I once dated a Catholic girl who, whenever we made out, had flashes of Jesus going through her mind, making her feel guilty. That, in conjunction with having to attend depressing, soul-crushing sermons at her church and dealing with her uber-conservative family caused me to never want to date another devout Catholic girl again.
So sure, I might find a girl attractive and wouldn't mind sleeping with her, but if I know that it would not make for a good relationship, I would not actively try to sleep with her or start up a relationship because I understand that would only lead to huge headaches for the both of us.