I have seen many people declare gay for you is a total fantasy of straight women and could never happen. Read jessewave's post and the comments on the subject. I've kept quiet because it did happen to me, but I'm a woman and my sexuality is fluid, and men are wired differently yadda yadda.
Today I read "I'm an otherwise straight man (who fell in love with his best friend)". This is a tale of a straight man who... read the title! If I'd been in private I would have whooped with joy! Yes, finally, a man who gets it!
Look, I'm not saying GFY is common. What I am saying is that it does exist. It happened to me and it happened to Mike (the man in the article). People are not wired all the same. They don't necessarily stay attracted to the same people/gender their entire life.
Only a person who has never questioned their erotic preconceptions could point at that situation and call it “Gay-For-You” because (again) to do so implies that sexuality is something you put on like a hat, and can take off just as easily.
No! No! No! GFY does not mean people are 'choosing' to be gay.They are attracted to someone, in this case their own gender, after a lifetime being attracted to the opposite sex. They don't walk down the road and think "Oooh, I'll pick a guy/girl today". It's the person they are attracted to.
Believe me, it isn't easy to suddenly discover you're attracted to the same sex. I explored it in Nothing Ever Happens as the man struggles painfully with the attraction, and I explored it Hairy Harry's Car Seat as something much easier. You don't put it on like a hat but it does exist. It really does.