Both of my parents were extreme hermits (I became more so then either of them). So, I would have to say that I've seen a relationship between two SPD work out to continue this messed up string of DNA.
I've dated a couple of people, slept with more (I'm not asexual, actually environmental factors kind of gave me an over active sex drive. Damn you jeebus (agnostic) for giving me a penis and the lack of social skills to use it. Cruel jerk.), and have had a one sided love for the past year now (another cruel fate, give me a girl I actually like a lot then fling me into the friend zone before the moves can be put).
Anyways, out of this I've found that for myself the people that can handle me best have a couple of underlying things going on.
1.) Have their own life.
Anybody who attempted to live through me vicariously was bored and done with me in a week. Definitely had to have a hobby that had nothing to do with me.
2.) Has an external social network.
I can be a shoulder to cry on, but I empathize about as well as a pet rock.
3.) Does not shut up.
I don't know why this on this one. Just a pattern I have found.
4.) Has a sexual appetite.
? - Dated an asexual for a while. The relationship was not fun. I've always thought that a certain level of physical attraction was required to exist in the relationship. Didn't realize just how correct I was with this one.
5.) Can deal with the fact that I'm an asshole.
I think that kind of speaks clearly.