You say that your T has only brought this up no more than 4 times in 10 years, and yet you tell her she "keeps bringing it up." You might need to start by putting a reality check on your own thinking. That averages out to mentioning it only once every 2 1/2 years. That is NOT very often, certainly not often enough to really qualify as "she keeps bringing it up".

That kind of suggestion can be made for a number of reasons, probably none of which is that she is angry with you or doesn't like you or is tired of you, etc. More likely, she sees you as either frustrated or not progressing, and she is doing the professional thing in letting you know that you do have other options if you are unhappy. If that doesn't apply to you, simply don't take her suggestion.

I can remember my T suggesting the same thing some years ago. He was simply concerned that I wasn't making progress, and wanted me to feel open to other options if that would be helpful. I told him that no, my lack of progress was not due to him at all, and I would be continuing with him. End of discussion. My pdoc, about that same time, asked me to go to another pdoc for a second opinion. He wasn't saying he didn't want to work with me. He wanted someone else to put eyes on my case and offer of suggestions for any changes in treatment. I really respected that from him.

It does seem like your abandonment issues have been triggered, but understand that generally things trigger us because we aren't seeing them through clear eyes.