I think that the "I'm not coming out of this box..." is hiding away. People will forget her, then she can re-emerge when she's ready. Perhaps a welcome vacation because she doesn't want people constantly reminding her of her loss, she'd rather just keep it in. Secluded elations, I've gotta admit, I had to look up the meanings of those words, so this could easily be inaccurate (I may not have understood them well) but perhaps it means... even when something good happens, your thoughts are still haunted by the sadness, so you don't really feel happy.
I think that the "I'm not coming out of this box..." is hiding away. People will forget her, then she can re-emerge when she's ready. Perhaps a welcome vacation because she doesn't want people constantly reminding her of her loss, she'd rather just keep it in. Secluded elations, I've gotta admit, I had to look up the meanings of those words, so this could easily be inaccurate (I may not have understood them well) but perhaps it means... even when something good happens, your thoughts are still haunted by the sadness, so you don't really feel happy.