Ask him what happens to him. Ask him if he wants to discuss the matter. You can say: "I've noticed that you've been very upset lately. Something wrong with you?" Maybe he wants to talk and I've been waiting for you to ask him. Therefore, listen to his response. Be silent and do not interrupt. You do not need to offer advice unless you ask for it.
If you do not want to talk, respect your decision. You may feel too hurt for the time being and think that it will collapse if you talk about it. Maybe you just have to process the situation and your feelings for a while. Give him a little time and tell him that you will be available when he wants to talk.
