Sometimes. ...

Not every friendship must end up in a relationship.  Sometimes people just want a talking mate.
Sometimes a laughing mate.
Sometimes someone they can have a drink with and talk gibberish
At other times someone to ask how their day went besides their mum.
Sometimes someone to do their assignments for them.
Sometimes, someone to write them a fat cheque or give them  some good cash.
Someone to pay  for them to get pampered at the spa.
Sometimes, a pizza eating mate or someone to buy them ice-cream though they can afford it. Not someone who expects them to constantly play mummy even when they lose their temper because they are the super coolest chick they know or the overly tolerant girl:no. Maturity isn't about age. Not someone to be their hand bag, stalker or regular...Stalking is an offence,  if you didn't know.  The little girl can teach you a lesson or  two too. The day they want more than these, they would state it. Don't assume 'you are' till it's been properly defined.  They can't waste your time when there was never 'you'. Know your place in people's lives and act accordingly.  It is not pride, it is called self respect. 
Friendship isn't by force.
Don't force people to be what they cannot be or do not want to be to you.
Ohhhhhhh and learn to accept and respect the decision of others. The fact that one girl turned you down doesn't mean it's the end of the world for you. The guys who end up insulting girls who turn them down, real gentlemen walk away with their heads high not  insulting girls.
Learn to accept that. Don't invest your emotions unless a person gives you a reason to. Obviously sometimes all they want is a friend they can do stuff with.