It sounds like your partner emotionally shuts down after a conflict. Speaking to a spouse that emotionally shuts down is just like speaking to a brick wall and you can’t reach them until they allow you to. It is almost like they are hitting pause on the relationship. The dangerous thing is that they get to control what is going on because only when they deem that it is okay to speak upon the topic, you guys can have a conversation. It is also dismissive and can be emotionally draining.

What I want you to think about, are your past conflicts.

How did they get resolve? Did they get resolved?

If this has happened one or two times, then having a conversation about how this affects you may be a positive move forward, but if this keeps going on, I think your best bet is for the both of you to speak to a relationship therapist since the line of communication between the two of you is broken. There needs to be a neutral party that can commence the line of communication between the two of you. 

There’s a difference between cooling off and being off and it is never a good feeling to feel alone in a relationship.

I wish you all of the best. Remember relationships are something you have to work on, on a daily basis.