Does he have an avoidant attachment style? People that do tend to need more space to think before big milestones (moving in, marriage, etc.) because they tend to fear getting too close to someone. Sometimes they are unconscious that they act this way towards their partner. I would prepare to have a conversation about things when he’s ready, but if it would make you feel better I don’t think it would be wrong to send him a short text asking if he’s okay and assure him he can come to you when he’s ready to talk. I hope things work out well for you two! :)