the young, slim, pear shaped ideal is based in fact somewhere down the line, however, everybody has their own preferences based, partly at least, on their own experiences. So some guys like skinny women with little boobs, others prefer slightly curvier and some like very large women - and every other variance in weight, height, shape and hair colour possible.
working on the same basis, all women like tall dark and handsome men with broad shoulders - but you don't see many women walking around with those kind of guys - they are with "average looking men" - that doesn't mean they don't love who they are with.
i think some parts of the media promote the idea that you're only successful if you're young slim blond/have a young slim blond on your arm and that can creates huge pressure to look a certain way (for men and for women!)
But in the end, looks fade and personally i think that the greatest success you can have is to grow old with the person you love the very soul of - in which case you really don't mind what they look like.