Myself and 2 close female friends have all broken up from LTR's with this type, and found many of our experiences eerily similar in the issues we faced.
My 2 friends were with ISTP's, and I was with a suspected ISTJ (I wonder now though, based on comparisons and further reading if he was infact closer to an ISTP).
The issues we faced that strike as equal were:
1 - Having our motives questioned alot. An example would be that my ex husband asked me what my favourite dish was, I replied and then was accused of merely saying I liked the same dish as him to impress him, even though he had yet to say what favourite dish his was, and it was just a coincidence. Or my friend to be asked by her ex ISTP what music she liked, and to then be accused of merely saying it to impress him. Again my other friend reports a similar experience.
2 - To be accused of lying all the time, even when there was proof that it was not a lie, and infact there was no reason to suspect a lie.
3 - To invent the most ridiculous accusations ever, example: I am half english, my mother is white. All 3 of us, my ex, my real mother and myself went to dinner together. It was a nice evening, that ended with him accusing me of hiring a white woman to pretend she was my mother because I was ashamed of being moroccan and wanted to hide it. When I attempted to show him my birth certificate, he flat out refused to look at it.
My friend reports that for her, her ISTP accused her of faking who she was, ie false name, false background, and refused to look at the evidence proving him wrong. Third friend reports that her ISTP partner accused her of pretending that she couldn't drive merely to seem more helpless to help attract a mate, when infact she can't drive.
4 - Suspecting intentions, ie try to do something nice and be accused of being up to something.
I mean there is no need to go on, but there are many points where the ludicrous accusations seem to come straight out of a book that they all studied from, even though they are all from different backgrounds, different cultures and had no contact ever in life.
The main thing was constantly suspecting the motives of everything, not being able to step back and listen to what is being said, putting a negative twist on everything. Having no factual recall whatsoever ie claiming to have not said/did something incredibly hurtful and cruel or violent, regardless of how many witnesses step forward.
Seriously, it's just insane.
Obviously there are many balanced istp's at this forum, without seeing that I probably would have developed a negative impression of them in total.
Still though, it's fascinating to me to see how alike our experiences were, and of course I would now like to hear your thoughts on what you think made these particular IST's behave this way?
My friend is an esfp and the other is an isfj, and of course my type is under my av.