Always have been single

I am a Man of age 27. Till now I have not been in any relationship with a girl. Nor any girl has ever fallen in love with me. I don't know why my life is devoid of a good relationship. I have always had communications with girls but they always term me "bhai". I don't know which girl will I get into a relationship. I can't randomly go to a girl and enter into relationship or communication right. I hate being single. My teammates often say why don't you get a girlfriend. Don't know why my life is like that.