Why some thing are so hard to let go of......

I went to a friends' party today...it was her birthday so we went to celebrate...we played a lot of childish games like Heart-attack and 7-Up....it was kind of fun.....we were like little kids playing all those funny games...her boyfriend was so romantic....he actually gave her a necklace inside a box which he have put inside the cake he brought for her. Suddenly that makes me sad...I wonder why I can't find someone too.. Maybe I'm destined to be lonely... I have a crush on someone...someone I know very long already...I don't know why but it seems I can't forget him..maybe i am just a person too stuborn to let go of someone easily...Maybe I should just tell him how I feel and then just let go...I don't want to hang on something that never will happen anymore...but I am so afraid I will lose him as a friend...I just don't know what to do.....i seriously sound pathetic and I guess I never imagine I would still like him after all these years..I have a crush on him since years ago and gosh that seems so long already since I am already 18....I hate myself...really... just let go...but I just can't...why???? Haiz I should actually get over it...