Um, given the average lifespan of the human male is 68 and a half... 43 is well BEYOND middle age!
I had a relationship with a bloke in his mid 40s when I was 18.
Frankly, I was his intellectual superior on many levels and I ended the relationship because the sex was poor (unimaginative, boring) and the bloke himself despite being well travelled and well off, was in fact also MASSIVELY boring.
On an emotional level we were pretty similar (both a bit sad and needy to be brutally honest) but I couldn't handle such a boring person who didn't want to try out new things or go to new places - not everyone in their mid 40s has done all the exciting things there are to do but he clearly had.
He was a nice fella though, kind and thoughtful, and even with the benefit of hindsight and a lot more life experience than I had then, he wasn't a perve or a weirdo.
These huge age gaps can work out, where hte younger party is emotionally and mentally incredibly mature for their age and has learned a lot... and the older party very young at heart and of course, both people on a similar level intellectually and ambition/lifestyle wise..
But sadly id say it is more common that theres a big imbalance of power and experience :(