The following sounds amazingly like my 5w6 sp partner is many ways.
I think that the 5 and Sp qualities are reinforcing, especially when it comes to control of physical environment. (Both Sx and So have expects that involve a bit more reaching out, at least on occasion.)
Also, (at least in my limited experience), 5w6s tend to be less emotionally attuned than 5w4 (or maybe it's more T vs F). This means that even when they do feel isolated and lonely, they aren't particularly good at knowing how to bridge the gap. It leads to an impression that they say that want closeness, but are both afraid to reach out and not that good at responding in an attuned way when one does oneself.
So, I struggle with my partner on this front. I try to keep in mind that the actions arising from his issues are not a judgment of my importance to him. I also try to express appreciation when he does try to reach out. Still, not a solved issue, by any means.