Well, I reckon I know what this is.
It is called 'Alexithymia' from the Greek meaning no words for emotions
Alexithimics and Aspergers share aspects of not being abe to articulate emotion so that's why there may appear to have a superficial similarity.
My DH is a Alex, it has caused a lot of heartache and pain. Living with someone who cannot demonstrate emotion is heartbreaking, been there, got the tee, totally with you OP.
In our case, we have only just made the connection, this has taken us 16 years! However, nw that we both know that this is the issue, things have got better. There is hope OP.
In my DH case it was exaberated by emotional neglect from his DM. This was triggered by the breakup of his parents marriage and his own mothers inability to show emotion. He literally shut his emotional response down in order to survive. Being brought up in poverty in a remote village didn't help either. Dad abandoned family early on, I've never even met him.
Alexithimia is a peculiar thing. In my DH's case, he can love and is a wonderful father. But he Los doesn't argue, doesn't find fault or pick. But equally would never plan a romantic trip away, misses out on the nuances of emotional communication, struggles with empathy. Unfortunately, the build of unexpressed emotions can lead to addictive behaviour in order to self soothe. My DHs was porn. This led us to the very brink and me to a suicide attempt.
You can work through this but he will need to explore his past. I would look to childhood, especially his parents. Was there a traumatic event that quite literally 'shut him down'?
Un MNetty hugs to you OP.