Hi there. So sad to hear that you haven't managed to find any "friends" in your life as such. Good friends - you know the true, honest, sincere friends are very, very hard to find. I have had plenty of friends in my time as well and alot of them are here one minute gone the next. Some people are just outright users that befriend you for some selfish reason only to discard you when it suits; sometimes circumstances change which prevents them from socialising e.g. having a baby; getting married, etc.; sometimes although people claim to be great friends they simply are so caught up in their own world that they have no time for you. Once in a while however you'll meet someone that you "click" with and want to remain friends with and the feeling will be mutual. Even then you'll need to put in a bit of effort by ringing them frequently, remembering birthdays, inviting them out or over to your home, etc. They should reciprocate by doing the same (this does not always happen). I have a great girlfriend who is more like a sister that I have known for over 20 years. She and I get together often and although we are both married we often just have time with the two of us so we can have girly talk but we also all go out and socialise as a group of a 4. So number 1. If you think there is someone you'd like to be friends with be proactive in starting and maintaining the friendship. 2. Communicate often either by phone or sms or facebook or whatever. 3. Initiate meeting up. 4. If it is a girlfriend - have time out just with her and leave the boyfriend at home. That way you can bond better and develop a closer relationship.
Also have you thought of joining a group - either a voluntary group or club or something which will give you the opportunity to meet new people and forge new friendships. Basically I don't believe it's you as there are alot of selfish people out there but be patient, be proactive and eventually you will find the right person(s). Good luck and remember that a true friend is hard to find.