Is it wrong to be in love with a gay guy?
NO NOT ALL and don't listen to people who say that there is. In fact, as many gay men have many female friends, you might find that they are easy to talk to and make for a great friend. The physical nature of beings means nothing except in a few instances and this is not one of those times. You are a being of spirit, energy and mind who is attracted to another being of spirit, energy and mind and the term 'love is blind' is completely true. If you feel a type of attraction or connection to this person then you shouldn't worry about what the world thinks you should just enjoy spending time with this person and if it leads anywhere then thats what happens.
Why do women fall in love with gay men?
There aren't really any strict rules regarding sexuality Homosexual men can be attracted to women, homosexual women can be attracted to men, heterosexual men can be attracted to other men (doesn't make them homosexuals), heterosexual women can be attracted to other women (doesn't make them homosexuals), heterosexual men can be attracted to homosexual women and heterosexual women can be attracted to homosexual men. We don't choose who we fall in love with and who we have feeling for. Just because someone has declared their interest in their same sex, that doesn't stop the opposite sex liking them; that filter only works one way!
So, to answer your question of if you like a gay guy and you are a girl does that make you gay or still straight the answer is in truth neither! It makes you a person who is attracted to another person. A "spirit" who has found another "spirit" and share something with and that is special for not all people have that with other people. You should meet and just live and not worry about what other people want to label it as cause their wrong. Don't worry about it just live life and see where it takes you.
Life's an adventure and it doesn't have to be constrained by rules. Many youngsters experiment with their sexuality, and try out kissing their friends etc, and that is because there are lot of chemical changes taking place, which can be confusing, but experimenting can be good because it can tell you what is and isn't what you want. I would never assume that you can turn a gay man straight, but he might be in a stage of experimenting, so you could just choose to stay close friends with him for now, especially if you find he makes a good friend :)