I’ve definitely noticed this. I rarely see average and below-average people in couples.
I suspect I know why this is. I approach all kinds of girls frequently. But unfortunately I’m only average looking, and so I fail 99.9999% of the time, even though I have low standards. Most girls find most guys to be unattractive and unworthy. Hence it’s mostly good-looking guys who get the girls. But because good-looking guys are hugely outnumbered by the overall female population, those good-looking guys get their pick. And of course they will pick good-looking girls.
Therefore average and below-average people are underrepresented.
Actually, I should clarify. I'm talking about young adults. There's plenty of average- and below-average-looking middle-aged and old couples.
Not true, I'm still single at 27 and do consider myself attractive.. All I ever see is below average looking people in relationships or getting married having children. I actually think it's harder to find true love as an attractive person.