There is a Pearl Before Swine Sunday Strip on that I was trying to find.
But anyway, I find much of this very annoying for very many reasons. As a starter, I have many friends. They come in many shapes, colors, sexual oreintations and genders. As far as I know, I have never tried to have sex with any of them -- and I'm pretty sure I'd know if I had. Having blanket statements that are invalidated by my own life always anoys me. This more than most because people who believe this cliche then circulate endless rumors and it can occassionally poison a friendship when a woman is persuaded by her friends that of course I must have designs in her if I am that friendly and helpful and so forth.
So, for those who still can't believe that a straight/bi guy cannot be real friends with a stright/bi woman, consider the following:
1. There is a difference between sexual attraction v. wanting to have sex. Many people seem to have trouble grasping this. If you look at someone who you find physically attractive, that actually does not mean you want to have sex with that person. Suppose I'm walking through a resteraunt and I see someone has a really yummy looking pie. I might find myself thinking, "wow, that pie looks delicious." That does not mean I want to grab a fork, walk over that person, and try to eat their dessert.
2. Even if you do actually want to have sex with someone, you're an adult and can control yourself. Contrary to myth, men are capable of actually controlling their urges. Really. We all got through potty training. It is entirely possible to decide that you actually would like to be intimate with a friend. It might even be a good idea under the right set of circumstances. Many men and women meet, become friends first, then decide to become physically intimate (either as a romantic relationship or as a "friends with benefits" thing).
But it is also entirely possible for a guy to rationally decide "no, I don't think this is a good idea. I'd rather not have sex with my friend even if I would like to do so." Again, that's the grown up thing.
I do recognize that for many men raised with the idea that it is wrong to display emotion -- especially before fellow males -- that finding a woman who is a really good friend with whom you feel you can share your emotions is confusing. But that deep intimate feeling you get should not be confused with sexual arousal. Nor should you feel compelled to believe that if you are emtionally intimate with a woman that it must logially follow, as the night follows the day, that you must therefore also love her in a sexual way. Which brings me too the next point.
3. The myth that men always want to have sex with a desirable sexual partner, and that they are utterly consumed with getting laid, perpetuates many real evils in the world. So many bad things get perpetuated by training men to believe that they are helpless little bags of protoplasm attached to a hunting annaconda THAT WILL NOT BE DENIED and that this is the natural and expected state of the world, is part of the justification for believing and/or tolerating very real evil attitudes. To list a few:
All gay guys want to have sex with heterosexual men, and if you ever feel for one second a flash of physical attraction for a person of the same gender you are totally gonna go gay or bi so STAY AWAY FRM TEH GAYS! After all, if all men are obsessed with sex, then it must follow that all homosexual men are obsessed with sex too. They can no more be "real friends" with a guy than a straight guy can be "real friends" with a woman. Also, in a world where sexual attraction is the same as sexual desire, if you ever feel sexually attracted to someone of the same sex, you must be gay. Q.E.D.
Both these ideas are utter nonsense and contribute much homophobia and sexual panic in straight guys.
Women who go back to a male friend's home or allow themselves to be alone with a male friend must be tacitly consenting to sexual advances. Again, if "everyone knows" that guys are going to want to have sex with any woman they can get their hands on, and a woman still goes to someplace where she can be alone with a guy, then she must be interested in receiving his sexual advances. After all, why else would she be alone with a man, since all men think about is sex. So going to place with a man where they can have sex must be consent, right? Q.E.D.
This contributes not only to date rape, but to tolerance of it. It becomes part of victim blaming. "Well, it's your own fault, you knew he was a guy after all. Everyone knows men are just incapable of controlling themselves." It allows the man to rationalize to himself "well, she is obviously interested or she wouldn't have come to my dorm to study." Being alone with a man of your own volition is thus transformed into the equivalent of stepping into a cage with a hungry lion. You knew the lion would attack, so you assumed the risk.
The idea that men are obsessed with sex and cannot control themselves becomes a self-fuliflling prophecy via indulgence and social conditioning. Much of our mass media is based around this idea of male helplessness. Guys espouse it to their fellow men, and judge them accordingly. Women repeat this to men and each other as a constant justification for why "men are pigs."
This helps create the culture of groping, objectification, and harrassment. After all, men can't help themselves. They are just little boys with a toy they can't stop playing with. We shouldn't expect better of them because they can't help themselves, poor things. The only way to deal with them is how we deal with naughty children. "Boys will be boys."
And, of course, the natural concomitant of this is that women are expected to be the "grown ups." They should be tolerant of harrassment because "what are you gonna do? Men are pigs." They bear at least part of the blame for date rape because, as the respnsible grown up gender, they should know that at any random moment any man can suddenly transform into a randy little grope monster like a kid going for the cookie jar. If you waren't prepared to "be the adult" then you shouldn't be alone with a man in the first place.
OK, rant done. To conclude, the "men can't really be friends with women because te man will always want to have sex" is one of many contributors to rape culture and sexism. Indeed, it is one of the fundamental justifications, because it has the appeal of reducing the male responsibility to control his actions. "Evolutionarily hard wired, can't fight the urge!" It should no more be tolerated or indulged than any other form such idea.
A man who cannot stop thinking of sex all the time, who wants to have sex with any woman with whom he feels a vague emotional connection, is not a "normal guy." He is at best immature and at worst obssessive and self-privileged to the point of danger. We should not as a culture tolerate this -- even expect it -- as the male norm.