I was married to an ISTJ. (Note the past tense.)
Actually, he's a really great guy. We were friends for years prior to getting involved, and I always thought he was entertaining, funny and witty, and yeah, reliable. Very devoted and loyal, very serious work ethic, very committed to his children.
We just spoke totally different languages. And while he's reasonably intelligent, he was just not able to keep me intellectually stimulated. He was interested in my existing ideas for the most part - unless in the midst of an argument - but he never really offered or inspired any that I found compelling. Damn, it makes me feel bad to say that, because it's not like he's boring or anything like that. He has great ideas, but they're generally only practical ones. Very rooted in the physical world.
Anyway, probably the hallmark of that ISTJ is that tenacious clinging to belief, which gets expressed through concrete practicals. If people want to get all MBTI about it, the shorthand would be Si perception of the world defended by Te. The thing, though, with ISJ's is that I've found them to doggedly defend their stance (and put forth their stance, if pushed), but if you manage to make a good case, suddenly one day they might just change their view as if it were always different and drop the old view, without any indication in the meanwhile they were considering a change. That drove me crazy at times.
DEAR GOD YES. That happened to me all the time. We'd have some really bad arguments, he would cling to his view tenaciously even in the face of solid, very basic logic, and then maybe a couple of days later, he'd completely turn around. But that only tended to piss me off more, because I never understood WHY we had to go through all that arguing. If he had simply considered the perfectly logical argument in the first place, we wouldn't have had to go through that!
He's also one of those people who can't see the difference between debating and fighting. It's all fighting to him. I can be cool and calm in the face of disagreement longer than a lot of people can, and indefinitely as long as the other party is being objective and logical as well. But when logic is completely disregarded and especially if it's treated as an attack, I can lose it. And once you get me pissed off, I can get REALLY pissed off. Of course, eventually the argument would end, and he would forget all about it, but I would stew about it for days.
So yeah, we pushed each other's buttons. I absolutely hate being pushed to the point of having these intense emotional reactions. I want to stay calm and cool and discuss things, but with enough pressure, I can erupt. So that always made me feel bad about myself.
Not really his fault, not really mine . . . we just weren't that compatible in a romantic relationship. Overall, he's a reasonable person as long as you don't challenge his beliefs too much. He's also an awesome father. I make sure he has a fair share of time with the kids and don't badmouth him, which he appreciates. He's devoted enough to them that he'll even offer - and sometimes insist on giving me - extra money beyond the amount of child support he pays. The divorce was not his idea and he very much did not want it, but he was never vindictive or nasty about it. I think it's helped that I'm the sort of person who believes in fairness, so I never tried to take anything away from him that he was entitled to.
So we're actually able to be very civil and even friendly with each other, doing favors and being flexible about schedules and such. We do still have our arguments, but I'm hoping that someday we might be able to go back to being true friends (it's only been three years, so we need more time for that).