I have known my husband for 35 years and been with him as partners for 20 years. I am on the spectrum and he is more marginally on the spectrum, so we share a number of issues and he can understand me more than someone who is totally NT. I think given our Aspergerian features, we live life more "side by side" than intertwined as I see with NTs. Each evening, we are in the living room, each doing our own thing but side by side. There is little interaction, but having the other there feels very nice and cozy. If there is something that comes up to share, then that is good, but silence is very nice as well. I can see how this allows me to be self-centred without being selfish.
I feel very lucky to have what I do with him. I don't think it would work nearly as well if he were not on the spectrum himself.