I've spent the past 20 years with two different partners, one 11 years and the second 12 years my senior. My experience is that when "they' start to really show their age it comes on fast. Granted both of them were extreme narcissists, so I/we are all better off without each other - they both miss me, I was terrific "supply" for them both. My next realtionship, should I be so fortunate, I want a partner ten years younger than me and def NOT a narcissist.