Can opposite-sex friendships last? Only if the two are mutually deceived:
The results suggest large gender differences in how men and women experience opposite-sex friendships. Men were much more attracted to their female friends than vice versa. Men were also more likely than women to think that their opposite-sex friends were attracted to them—a clearly misguided belief. In fact, men’s estimates of how attractive they were to their female friends had virtually nothing to do with how these women actually felt, and almost everything to do with how the men themselves felt—basically, males assumed that any romantic attraction they experienced was mutual, and were blind to the actual level of romantic interest felt by their female friends. Women, too, were blind to the mindset of their opposite-sex friends; because females generally were not attracted to their male friends, they assumed that this lack of attraction was mutual. As a result, men consistentlyoverestimated the level of attraction felt by their female friends and women consistently underestimated the level of attraction felt by their male friends.
At some level this is automatically true. Assume simply this: all men are attracted to all women. Then which women will the men be friends with? The ones they expect to be able to hook up with. Of these friendships few will survive: if she figures out he is attracted to her she will either hookup with him (if its mutual) or run away (if its not). Either way the platonic friendship ends. The only surviving friendships will be those in which he thinks she’s attracted to him, she’s not attracted to him and she hasn’t yet figured out he’s attracted to her. QED.