Dear Nina:

“what if he calls for his keys and we get another shot to talk things out”-

I think it’s better that you do put his keys “in the mailbox and move on”, because the scenario of him meeting you in person so to get his keys, is not the only scenario for a future talk between the two of you. Besides, it is almost like you are holding his keys hostage.

Return his keys. He will feel better about having his keys back, and feeling better, maybe, just maybe he will want to talk with you again.

“don’t  know why he cried that much. Was it because..?”- I wish you knew and wonder why he didn’t tell you.. Maybe when you place his keys and a card in his mailbox. In the card, gently offer him to talk about what troubled him so and write to him that you would like to understand, to learn from what happened. What do you think?

anita