I agree that other cultures do often value spending time with extended family more than American culture does. I can see that some of the difficulty is probably due to a cultural difference – like about how they don’t have much food in the house or etc. Some of this seems like something else though.
It does seem like he isn’t very emotionally available when people around him are in pain. It sounds like it'ss a very hard thing for him to tolerate. Whether it is his mother, his father, the older couple at the hospital, or you, it sounds like a pretty well established behavioral pattern for him to not have much of an outward reaction. It could be due to culture, defense mechanisms, personality, possible pathology - or a mix of all of it.
It also seems clear that his lack of response, empathy, and ability to be emotionally intimate when things are rough – this is routinely scares you, again and again. But you stay.
There must be reason you stay even when you get scared by this well established pattern? Is it because you don’t know if you can find someone better, or because the good times outweigh the problems? or because you are hoping things will change when he gets into therapy in September? I would probably struggle with leaving, or wonder how I could help change things, and feel scared at times...
For people with trauma, my therapist says we will often subconsciously look for and be drawn to people who can’t be very emotionally intimate for two possible reasons: 1.) it echos the trauma of the past – we find someone who will abandon us once again, and the person tries to subconsciously solve it through solving problems in the new relationship 2.) because on some level, it is “safer” than people who can be more emotionally available.
It might be worth talking with a therapist about this relationship and how to sort it all out. It does not negate any of the good work and healing you have already done. It just might be worth looking at this relationship with someone who can give a professional perspective, especially if you plan to stick it out for the long haul with him.
I’m not sure if any of that is applicable for you and this situation. Just some thoughts to consider. If I'm off the map, just disregard.