I dont know if this is just mere coincidence but I came to realize that friends around me are (still) single on their late/r years :) no offense meant. I am not Dr. Love neither the expert. I am just trying to iron out the possible reasons that barred them to having a relationship.

True enough, life is a roller coaster. It is never fair. But having a partner is helpful (in some way) that you have someone to rely on even if the world turns its back on you. Yes, we have friends and of course our ever-loyal families still, we feel certain emptiness inside. A feeling that is beyond the universe can explain neither can a wonder pill heals.

Here are the lists of possible reasons:

One feels unpretty. If we are to tally, this characteristic will get the highest number of votes. Apparently, this may be significant. But come to think of it, physical appearance fades. It surely would not last for a lifetime. And what sucks about this is that it deceives a lot of people. If youre unpretty, others would see you unpretty in and out. People would even disgust you. It pains to know but this is true in the society we exist. We always have to consider what the society is going to say. We always have to act on the way the society would accept it to make us feel we belong.
Lesson: you only have one life to live. Prove the society wrong. If we keep on minding what other people would say, we would absolutely miss a lot. Dont let the physical beauty stop us from being happy with somebody. Of course, it should be a mutual understanding. Meaning, we should treat the same thing to that somebody, not to see him/her unpretty :)

No time for love. Most career-focused people would fall under this. They would reason out that work have been killing so much of their time. True but false. No matter how busy you are, find time to (atleast) meet new people. Yeah, you are free to scuffle my comment cause I myself dont go out. I have my own reasons so bug off! Hehehe. But the irony is that, having that somebody does not happen in 24 hours. It is like a seed planted waiting to grow.
Lesson: pray. this works mind you! :)

Enjoying single hood. No man is an island. Being single is great. But it is greater with somebody to share accomplishments and dreams. That somebody would serve as our inspiration to work more and do well. We often think logically that being single would blame nobody but just us. True again, but it is better to have somebody listen.
Lesson: let go of singleton. Give it a shot!

Afraid of commitment. This is one hell of a reason for people who have been there done that. People who have been torn so many times would have no courage to risk again. Well, life is not a bed of roses. Things happen for a reason. If we were to analyze, what lesson learned on the past would definitely be the foundation to face what is in store now and the future.
Lesson: take the courage to let go of the fear and get a life!

Not over him/her. If you are holding back on that feeling for a long time and you think there is a lean chance of getting back to that somebody, dont let it be the reason to restrict yourself from meeting other people. It would be unfair for you to suffer on it. How sure are you that the other end feels the same way you are? So think again.
Lesson: if you are meant for each other, no matter the distance and time, you will still end up together. For the meantime, go party!

Too late for me. It is never too late. If you think you are pass the calendar age to be dating, dont be! Who set a rule on that? Nobody. So dont feel shamed just because you missed to date would prohibit you from dating now. In this generation especially for women, either they get impregnated during teenage or give birth at early 30s and 40s. Dont feel too sorry for yourself. Somewhere out there, you are not alone.
Lesson: if you are over the courting (I dont know if this is still being practiced) , welcome cyberspace! You would soon realize that there are other people longing for the same thing you are. So go. they are just one chat away!

There you go. These are just some of the insights I have in my head that made me wonder. I know there are hundreds (if not thousands) of reasons for being single. I have not included the reasons such as: religion issues, she/he is affluent and she/he is not, standards-based judgement, etc. these are given situations that would need a different level of attention. hehehe. these are just hypothetical instances in my mind. respect it the way i respect your judgement :)

Well, this is it for me. I hope I made sense after all. Ciao!