Hi
@MandyLou Assuming that he truly doesn't understand why you are upset by distancing behaviour. lack of showing care. and no communication (rather than him caring but nor being able to communicate that):
I think a few things could cause it. 1.Sometimes, in life. people who are in very intense pain get so caught up in their own experience they loose touch with others perspective. They become self fixated as a survival method. 2. Some people haven't had any experience of emotional closeness and haven't practiced thinking of others. They don't yet know how. 3. And some people have low empathy abilities. Those with PTSD, like anyone without it, vary a lot when it comes to empathy levels. For example: there are quite a lot of people with PTSD who have over developed empathy levels. All these relate to the general population and not just PTSD.
If he truly doesn't get it and its 1. then you should be able to discuss this and create a more balanced relationship. He may still need to isolate but your feelings should be understood and validated. If it's 2. then it could potentially change. You would probably have to be very patient and work at it. If its 3. then I think it can be tricky and there are other implications. It doesn't mean you can't have a good relationship. You might have to be realistic about how much he can understand you and may have to spell things out very clearly (I've heard this is the best way to communicate feelings with someone with low empathy [unless they are sociapathis of course]). Nuances and hints or subtlety probably won't work.
Ways to tell if its these issues rather than him just being in shutdown:
If the thinking and behavior only happens when he is in shutdown then its likely about flight and fight and working on PTSD skills is the answer. And communication and compromise between you.
If his feelings about this and his general personality traits remain consistently headed in this direction then it may well be one of the above factors. The trouble for you is if he is finding it hard to speak about this then it may be hard to differentiate and get that info from him. I personally would watch how he is when he is at his least symptomatic.
Me? I have a history of feeling way more for others than I do for myself. I'm not proud of that as it wasn't healthy. In those states I am unable to say anything and let people down badly but I feel terrible about it. Normally what used to ensue was a period of terrible self hatred, self harm etc which didn't help anyone. I am more balanced these days and care more evenly for others and myself. My point is that it probably would look very much the same from the outside which doesn't help you in your day to day life. But if you want to figure out who he is as a person and at least be validated by him then look for information outside the isolation itself. Regardless you may feel it is all too ,much for you and that would be valid.
PS. there are always PTSD symptoms present of course and speaking about personal things tends to be hard for a lot of us so what I meant was to look at more general behaviour to you and others. If he can't discuss this directly with you.