Clear communication as to what is happening for us is most helpful, for when you go into overwhelm others may see you as being narcissistic. What is actually happening is that you have gone into survival mode, and that, by its very nature, means that you can only pay attention to yourself. At these times, it may be necessary to take time alone away from as many external stimuli as possible. This needs to be presented as a way of taking care of yourself, so that you can come to terms with exactly want your overwhelm is about. Once you are out of overwhelm, then you can return to your regular mode of making contact and interacting.
Boundaries are also very different for USPs.
That means you have a very unique opportunity to learn about how to stay with yourself as well as to be deeply connected with another. This line between you and another is a thin one, and it is easy to cross over and believe that you have lost yourself. You are totally with yourself, but still acutely aware of the other as well. I feel that this may be a slightly different perspective on boundaries that many psychological therapies don t acknowledge. There are several basic approaches I suggest.