An occasionally heard complaint from women about their long-term partners: “I have grown so much since we met, but he has not changed at all. I feel like I have out-grown him.” (with variations). This has always struck me as odd, because in my experience women tend to be the ones who develop less (notwithstanding the fact that humans in general tend to be slow developers). Possible explanations:
Obviously, it may simple be the case the she has developed faster. Note that women, in adulthood, develop slower than men on average; however, there is always a significant portion of individual variation involved. Consider, by analogy, that many women’s world records in athletics are sufficiently strong that they would have won some Swedish championships for men.
The woman has noticed a development in herself, but overlooked a similar development in her SO. (This is a common human tendency, of which we should all beware.)
Her SO is older than she, and through diminishing returns has developed less, without necessarily being a slower developer. Consider, e.g., a woman of 20 who meets a man at 25: Comparing their development in the following five years, she moves from 20 to 25 and he from 25 to 30. Statistically, it is only to be expected that the younger individual develops faster.
A particular special case is when a women is originally attracted to a significantly older man because of his maturity, say a mid-twenties woman to a mid-thirties man: Because the difference in maturity will be partially due to the age difference, diminishing returns can cause a grave disappointment over time.
Similarly, a woman may originally have teamed up with a man on a similar maturity and development level, who incidentally was a few years older. Here we will not only see diminishing returns, but also a difference in “base rates”: Because they were originally a good match despite the age difference, it is likely that the woman is a faster developer by nature. Correspondingly, she will be likely to move ahead over time. The same applies between very young people, where their young age have prevented them from moving apart, but the originally small difference will grow over the years. (The latter is a more common situation with the sexes reversed: Two twenty-year olds hook up, and five years later the man has come to realize that his woman is still just a girl.)
Young women (and men) often pick partners for the wrong reason: That someone has a leather-jacket and a motor-bike may be impressive to inexperienced women, but also tends to correlate negatively with intellect; whereas book-worms show the opposite profile. Correspondingly, women often select exactly those men who are likely to be weaker in developing their intellect and maturity. This skewed sampling can obviously cause many cases of mismatch.
As remarked in a similar discussion, women often have a misapprehension of what maturity means, which can lead them to entirely misjudge the situation.