Jesse wasn't my first dip into the younger dude pool — we connected after I'd had a handful of casual things with guys four or five years younger than me.
But this kind of thinking conflates practical responsibility with emotional maturity — which isn't really accurate.
We might think that certain concrete markers of adulthood — a prestigious job; a working knowledge of personal finance; properly assembled Ikea furniture —signify a related degree of emotional maturity.
In our culture, dating an older partner is often seen as a status symbol for younger women — we're often told that older partners will be more financially and emotionally stable, which is why being courted by an older partner is often seen as a compliment, a confirmation that you, indeed, have your act together and are desirable.
This is probably why heterosexual women's age preferences in partners tend to skew their own ages of higher (while heterosexual men's tend to skew younger).
In my own anecdotal experience, I've found no correlation between age and interest in a serious relationship.