For the last 15 years of my life, i have been ignoring an entire market segment, namely those of the genus The Ragbag handily plotted out the socially acceptable upper and lower bounds for dates at various ages in the chart below: Notably, the chart also implies that there is a socially acceptable lower bound for your age: below the age of 14, by this rule, you shouldn't be dating at all.
Incidentally, if you're wondering how well is this rule adhered to in practice, the dating website has done an extensive analysis of age preferences amongst their members.
But it was The Ragbag who pointed out that this rule has a duality: for the date to be socially acceptable, the rule must be adhered to by your date as well.
In other words, there's a socially acceptable maximum too, given by inverting the equation: It was only yesterday that i realised that the rule of thumb for dating people of different ages (the “half your age plus 7” rule) determines not only the lower bounds for dating but the upper bounds as well—that for each ½x 7, there is a corresponding 2(x-7).
Buunk of the University of Groningen, examined desired minimum and maximum ranges across different ages by approaching people in public spaces—railway stations, libraries, malls—and asking them (anonymously) what ages they would consider appropriate for five different levels of relationship: marriage, serious relationship, falling in love, casual sex, and sexual fantasies.