I am in love with a girl who loved someone else. But that guy is already in a relation with another girl. But she still can't let go off that guy and says he is the only one she ever loved, do you think I should tell her how I feel about her? She is a great friend of mine and she considers me the same. I fear I may lose her as I a friend as well if I propose, What should I do?

You can propose, and risk losing a friend, but don't expect much from a female that loves another, as hopeless as that may seem.

I would not, because I think it may be hopeless, and may be looking for better options for romance than a friend in LALA land.

If she is in love with someone else your telling her your feelings is not going to change what she feels.
Be friends with her if you want, but I'd look elsewhere for love.

If you two are good friends, she must know already how you feel. Just the way guys look at girls, a girl knows.

But if you're not that obvious with your actions, then yes, let her know. But make sure you're truly prepared for what she has to say.

There is nothing wrong with being rejected. Life is too short.

“Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your hear.” – Steve Jobs