I'm married to an ISTP, and being really duty-driven myself, I cannot wrap my head around his reaction to basic expectations (if someone who rarely cries is bawling, hug them. If a baby is crying, pick it up. If someone says, "hi", saying "hi" back is generally considered polite. That kind of thing.)
Is my husband just a royal jackass?

Or is there some element I'm not taking into account here? A reasonable side that could be appealed to? I'm generally willing to lower my expectations, but it seems like no matter how far they're lowered, it gets taken down a rung or two further.
What I'm sure feels to him is logical energy conservation seems downright inconsiderate and cold to me. To the point that I'm getting fairly bitter about it.

It's possible I'm being a jackass about it, and not realizing.
MonkeyGrass,
I know EXACTLY what your talking about. I have been with my ISTP for 4 yrs now. Before getting really into mbti, I too thought he was a jerk. (Still do from time to time.) I now realize that its simply a difference of expressing love.. but I have ALSO realized that, especially as a feeler.. the relation may be too much of a struggle, *for me personally*.
In hindsight, I sometimes can't believe that I had been so blind to carry on with such incompatibility. That socionics duality deal is a bunch of crap. It says ENFP/ISTP relations are the most ideal.. not in my case! (Though the typing is mbti, not socioncs so maybe theres a difference?)
Anyhow, I just wanted to tell you that some of the things you mention have rang in my mind many many times, verbatum. Like "I'm generally willing to lower my expectations, but it seems like no matter how far they're lowered, it gets taken down a rung or two further."
Some things I've noticed, and this could be stereotypical or could just be us.. is that
when under alot of stress I can become pretty demanding for emotional support. I need those words of affirmation, support, guidance, more than ever. And when I do this, he totally disappears. Sure, he might be in the same room, but he will not talk, not respond, absolutely nada. It's ONLY when I lay off of him, expect nothing, require nothing, that he comes to life and acts more caring. Its really bizarre!
Part of what drew me to my ISTP is the fact that he seemed so emotionally disconnected. I thought (stupidly) that the ONLY way someone could be like this is from some past hurt, disapointment, rejection etc.. So heres me.. this passionate, warm, open, loyal ENFP.. and I'm going to save him. I'm going to show him that not all people are shit. It's okay to show your feelings and put yourself out on a limb. Not everyone will screw you over. Little did I know at the time that there was nothing in his past that shut him down. His mom and dad are great, loving people. He was a spoiled rotten only child. Its a simple personality preference. Wish I knew then what I know now.