why is it so hard to find a boyfriend?

all the guys are either dating or they are not interested in me at all. one of my acquaintances was kidding when she said her sister has been looking for a boyfriend since first grade and now shes in third so it hasnt been that long. I cant even be friends with guys because they say they have girlfriends so they cant be friends with me, its so unfair. it is just so hard to find friends when your single.