I mean, often my wife is the only person I see for a several hour stretch. And it's somewhat sad and lonely when I experience something and it's not really something I can share fully with her -- because it's deep and specialized and nuanced in somewhere that I've obsessed.
But-- how can anyone expect that of anyone? How boring would life be if I'd found such a close twin of myself that all the weird, esoteric stuff that amuses me made sense to her? She brings her own perspective and abilities, and the cost of this is that I don't get to see myself and my little obsessions mirrored every second in her.
A partner can bring an awful lot, but they can't bring everything all of the time.