I guess time is the answer. I still haven't been in a real relationship yet, but there were people I really loved, and who I was close with for a couple of months. Only they all rejected me :). At that moment, my world always collapsed, but after a while you start finding new things that interest you, new joys in life. I found my music through rejection, which is quite a paradox. Because right now music is my main interest, and one of my greater joys in life (I don't dare to say greatest), and I acquired that through the toughest rejection. The deepest fall got me on the highest top to say it metaphorically.
When I look at the times I got rejected I can only smile. I believe it was for my own benefit. Rejection played a major part in my depression, and made me feel so sick I couldn't take it any more. So rejection also brought me to my current state of happiness (I feel almost as joyful now as when I was a little kiddo running around without a single worry). So when I look back at it now, I smile because the rejections turned out to be for my benefit.
Of course, I am not you, and I don't know what I would be like now when I did had a relationship. All I know is that embracing the fact that it goes the way it goes, and thinking it happens for your benefit, will make you smile. I can also see it from the other side, the rejections are bad and ruined my life, but I will only hurt myself more by thinking that. So I try not to, and after a while it gets easier to see all the positive instead of the negative.
Love yourself NW, and the love of others will find you, I promise.
Acceptance is the key
Existential depression and Insecurity
Try to keep smiling! :)