There's a ton of research on this sort of thing, all you have to do it look for it. When you do, you find that men and women are supposed to complement each other.
Ultimately, a good relationship is good for you, so try to get a good relationship. That's really all there is to it.
I don't know about the 'admin/mental load.' stuff, but if that were a factor then women wouldn't live longer when married, yet they do.
To your other points, men tend to select for beauty and fertility (younger), whereas women tend to select for wealth and status (older).
#NotAll to this and anything else I say, obviously, but this is the trend.
Women are more social than men are (I.e. more friends of higher quality). This is partly why men live longer when married, as they gain access to the woman's social resources. Another reason is that women can care for them, and give them a reason to care for themselves. (The exaggerated stereotype of a single man living in a barren flat with just a bed, chair, and TV, exists for a reason.)
Social resources are linked to life expectancy, and it's why women don't tend to fare as badly when their partner dies; they usually have a good social support system, whereas men do not, and as such they tend to wither very quickly if their wife dies.
That said, if you lose your beloved husband of many years then it's not unreasonable to expect that a woman will also suffer a reduced lifespan. This is backed up by a lowered life expectancy for the woman where there is a large age gap.