Answer’s pretty clear (at least, it is if you’re a guy at Utah State University’s library): Because we’re men, and we have those feelings.
This clears up why all my very-close straight guy friends from college dropped off the face of the earth once they got married.
Do you think men and women can be friends? Does a bit of attraction get in the way of friendship, or does it enhance it?
P.S. Why didn’t I go to Utah State??