Been there Maggie. All you can do is accept the situation and live with it. I felt like that for a number of years and didn't think that it would ever really change as I couldn't imagine meeting anyone else who would make me feel the same way.
However, I always told friends that there could come a day when I would see someone and things would change and that day did come. In fact, I'm happier, I think, with the man I now love than I ever would have been if the previous relationship had worked out.
I found that talking to friends helped to keep the hurt under control and keeping busy and involved in other things made for less time for moping about the lack of a relationship. Didn't stop the hurt altogether, just made it easier to manage.