Well...it has happened to me many times...especially in high school and when I lived at campus, during my university studies. I've never been attracted to women. Only to men. But I've always found easier to have female friendships...so I've always had women as best friends.
Before I came out and confessed my sexuality to them, some of my college female colleagues used to compliment me all the time. They were very sweet and used to hug me all the time...and I hadn't realized yet they liked me. One of them even hit on me explicitly; another one, a very pretty girl, with green eyes and red hair even tried to kiss me. I pushed her back, immediately, telling her: I am sorry...don't.
I have to admit it is really frustrating to be hit on by females, because I feel almost guilty for not liking them. And I know how it feels not to be loved in return, so I can relate. It is also frustrating because I would like men to be as adventurous and daring as those girls...and to hit on me ...
it seems that men don't easily fall in love with me ....women do.