Nubile young women with older men

Is there ever an end to the annoying "may-december" depiction of nubile young women with older men? The pattern exists in real life but sometimes when encountered in SF one can't get over the idea that it's some sort of gross wishful thinking on the part of the male writers.

Some of the many, many examples include:

• Y.T. as a quite young woman in Snow Crash by Neal Stephenson - Interestingly turned out as a type of female empowerment, and the guy is not the protagonist.
• Wednesday Shadowmist (aka Victoria Strowger) - young female protagonist with an older male protagonist -- a world-weary "warblogger" -- in Iron Sunrise by Charlie Stross - When it happens in books by guys who seem to have a social conscience or awareness, one wonders, sadly, whether they have really considered the political implications of this? Is it needed to adult-ify the novel, to some extent? The sheepish internal commentary by the male character acknowledges the impropriety of it but it still comes off a bit creepy.
• Many, many novels by Robert A. Heinlein

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