What he says and how he feels just contradicts itself. If that one piece of object didn't mean so much to him he wouldn't act surprise and uncomfortable upon seeing her take it out and not just that refused to take it.Right? I think he was hoping she'd keep it too. The look he gave her.... like, "girl, take it back!" hahaha
He could easily take it and throw it away or keep it but he knew how much it meant to Mintha especially the meaning behind it. He didn't want to lose her and have her part with something that they have together...the pain he expressed when she threw it away the second time was more than any words he can say. It looks like he followed where the harmonica landed before coming back and stared at her in disbelief that she went through with it.