Most of my friends and acquaintances are committed to long-term relationships (mid-late 20s age group). I've had trouble in this area due to certain personal reasons, but my personal observations lead me to believe that I'm atypical in this regard.

Keep in mind that people with good social skills tend to have more friends, so your selector maybe biased in that regard.

Yeah, I've too much underrated observations like this in building my model above. Looking around, at age twenty-two, I notice most of my friends are still single, maybe 40% of them at most have some kind of relationship in any given month, but those relationships aren't stable over the long-term. I thought my model still might hold because I notice other people in my social circle at or around thirty are single, too. However, single people could select themselves to hang out with other single people. People closer to thirty than twenty who are single may be unusual in that they're more likely to hang out with people a few years younger than them, who are more likely to be single than not. So, the only young adults near 30 I'm observing are the ones who are hanging out with younger folk closer to 20 or 25.

I fell prey to confirmation bias here. I had no observations of social circles which are predominantly 25-35, rather than 20-30, which might be lousy with long-term relationships. Maybe this is happening at fondue parties or something, which I and my friends never hear about now, but will be doing in five to ten years. Thanks for the data point(s)! I think I was wrong before, and I think I know why!