All the above said answer are true.. I would just say that when she moved away from u to someone else. So U too have to move forward. That doesnt mean u have to date with someone..Try to strive hard to achieve greater in life that can be in terms of career, family life, personal life, ur hobby, passion, making friends etc. and show her ur achievements. You still think of her because u have innocent heart to still love her. Everything happens for the betterment, if u would have married her, your life would have been more miserable, you dont know. Give time and space to yourself and try to move ahead in your life. Might be this was an opportunity from god to understand urself. Praise god all the happenings in your life.