I have to agree, it's not so much the looks fading in men that puts women off as they get older.....
It is - as someone said - the fact that many men (by around 45 - 50 y.o,) become whiny, moaning, ranty, chuntering-under-their-breath, hating the world, 'life fucking hates me' whingebags, who complain constantly about queues, immigrants, money, their job, their work colleagues, their aches and pains and ailments, the NHS, the police, doctors, nurses, dentists, the neighbours, his kids, other peoples kids, the cats, the dog, the bastard who parks his car in front of the house when he doesn't even live in the road, every meal they're given (by the wife OR in a restaurant or car,) the extended family, and of course, the weather.
That's when he's not thinking he's George Clooney or Brad Pitt, that every woman he speaks to fancies him and thinks he's hilarious, no-one at work does the job better than him, and that even women half his age secretly have a crush on him, and think he's a wise and witty silver fox.
I know quite a few many men like this. ^ And I think many other women do too! And I think it's hilarious and ridiculous that it's traditionally women who are supposed to be the 'nagging' ones. I know WAY more moany, naggy, miserable men over 45, than I do moany, naggy, miserable women over 45. And I know a number of long-suffering wives who are putting up with a man like this.
Also as @IcedPurple said, despite the belief that men age better than women; I know many more women over 45 who are attractive and fit and look great, and who really take care of themselves, than I do men over 45 who look great.
And yeah, many of these middle aged men - especially the single ones - are under some bizarre illusion that all women fancy them, and can't understand it when they don't, and think there must be something wrong with the women.