Easiest, most direct solution is to talk to your friends - maybe they don't realize they've been ditching you so much and that it's really hurting your feelings. More complicated answer - start looking for new friends in new places - take some time to develop a new interest of your own that you didn't previously share with your friends (or maybe have neglected), and you'll be introduced to a whole new group of people. Stay in touch with your now-partnered friends, but let them know that after x number of broken 'dates', you're a little leery of making plans without assurances that it won't happen again.

This is very frustrating. Find friends that are also single and also maybe ditch your friends too, to show them how it feels. If it continues explain how this makes you feel. If they are a good friend they will understand. If not, well....

Well, i would spend more time and blatantly do so, with single other friends and if your friends with partners ask you why you are hardly with them, just say you dont think they have the time for you anymore so you've found other people who do. Or, when they get dumped. turn your back on them.