This may sound a little rough, so I apologize in advance if it does. Or unfinished...it is my way to toss things out there and do the refining out of my head.
I'm very close to an INFJ young lady. I see her doing something like what you describe (if I'm reading this close enough). She will shift in order to fit. It's not usually anything radical but it frequently happens. I mean shifting for external harmony or common ground. For her, it may mean 'abandoning' a position for the sake of harmony with me or her brothers. From her perspective, it's rough (she's the only Fe-user in her close circle) because she feels like she's doing something for us. From my perspective, it's irritating because I never asked her to do this and now I feel like I'm supposed to be grateful for something I never asked for. And it can give a slippy feel. I do not understand her need to find agreement/external harmony before we can proceed in a discussion of things. To me, even the assumption that this should be done raises some hackles. You saying "her terms and grounds" sounds very much like this. And you're right, it's natural to her but she's not going to see it like that...I have a hard time with it...but maybe you do because the issue is not being met on "our grounds and terms"? Are you saying you're feeling resentment because you feel like you're doing something for her, for your relationship and she can't even bother to do the same? Or even acknowledge that it's going on? That's what it seems like I'm hearing but I could be wrong about it.
At the same time, I understand the exhaustion that can result from this. As an Ne-dom, I often feel a strong pull to "respond". Nobody is asking me, but it's just my natural way of being as an ENFP. I can feel exhausted and put upon because of this and place the blame on others instead of just ignoring the (mainly unspoken) pleas, wants, and needs of others. It wasn't the other person(s), it was me not being able to deal with the anxiety of not responding and my own identification with being a responsive person to those I'm close to. But I stopped that mess. It's good boundary making and necessary in a healthy relationship. It kinda sounds like this is part of the problem and if something's not done, it's not going to end well. Resentment will eat through any bond. FLD mentioned this in his post.
Your INFP may be more understanding of you not responding in the manner that you have...hell, she may not even notice that you're doing what you see yourself doing because Fi doesn't work that way at all.
Do you have an examples of how you would prefer your relationship to be?