I'd just add that "loner with loner" creates a big opportunity to become overly dependent on each other.

I've just skimmed through this thread and don't remember who it was whose DH felt that her life was interfering with their together time ... DH and I struggle with this, and we're both retired! IME it's got nothing to do with how much time you actually have or spend with each other, and everything to do with how much you rely on each other for human contact and intellectual stimulation.

For all we go over and over it, I don't seem to be able to explain that normal people have jobs, normal couples have one job each, and my 2-3 hours a week job and 12-20 hours a week training are NOT what's keeping DH from doing what he wants to do.