Loneliness is a choice and sometimes we cannot avoid it. We just surrender to the condition and accept that we're so lonely even in the crowd. It seems that your best friends cannot fill that gap. It seems your girlfriend/boyfriend cannot make you complete. But, we need to realise being lonely is so human.
Perhaps you just broke up with your loved ones or you're running long distance relationship. After all, it is still a negative feeling, of being lonely. Here comes the ideas to cope with your loneliness that I hope it works on you.
Remember that we all feel lonely at times, not only you, but many out there.
It is something normal, and you cannot let yourself dragged into more sorrow and sadness.
Find something you enjoy and that interest you.
Being absorbed in your passion, hobby that can change the way you feel or simply put your attention to your work, but not being a workaholic.
Don't think that sex will help to fill the emptiness.
If you're single and simply plain lonely or you're running LDR, it applies for you. It won't bring lasting meaning or fulfillment to your life. In fact, you're likely to feel lonelier and more dissatisfied. I never experience it personally, something like booty-call or so. I just know the term booty-call few weeks ago. Pardon. If you're with your partner, it's your choice to have sex. What I mean is, don't have sex with the one who's not your partner just because you feel lonely.
Even if you're in a happy, and strong relationship, you cannot expect your partner to meet your every need.
We still need other friends and other things that we can do. You can still meet with your friends. She/He can do that to. Loosen up and trust them, they'll pay you with greater love and affection.
Make sure you're not living in some kind of fantasy.
You think too much of being Bella Swan or you're too much falling in love with Ryan Gosling (okay, that's me but it's just admiration, not a huge fan). You're longing for a love life like in the movie. It is an imaginary world that can never satisfy. Live your real world and work on real relationship.
Don't wait for other people to phone or contact you.
Call your friends or arrange something to meet up with your friends.
Don't turn to drugs or alcohol to block out how you feel.
That's a temporary solution and won't help in the end. You just devastate your own self. Heck, who wants to be with alcoholic and a drug user?
If you're afraid of getting close as you've been hurt in the past consider getting counselling or psychotherapy.
Believe me, you can heal your scar and you can learn to trust again.
Good luck :)