I know exactly what you mean. It seems like every time I have to go out, I see PDAing couples in the grocery stores, etc. Makes me want to die. The worst recent experience I had was when I went to an anime convention a couple months ago. Couples everywhere as far as the eye could see. One of my stupid dreams has always been to find a girlfriend who shared these same interests, and go to a con together with her some time. So it hurt even more.
People have told me over the years that it's because I "don't try," etc. They're so ignorant. That very convention had a dating event that I tried going to, and the ratio was absolutely devastating. About 25 girls showed up versus 600+ guys. People don't realize how impossible it is just to find someone who has shared interests, let alone the nightmare difficulty that comes after that of being good/attractive/etc enough for them to consider you as dating material. It's also exponentially harder once you're on the wrong side of college age.