I can't quite pinpoint

Is the caption her declaration of independence?  She needs no one to coddle her, take care of her.  She is only dependent on herself. Was she reminding the person who originally held this photo that she doesn't need them? That she can, she does and she will continue to be her sole protector and caretaker.

Or was this sent on as a benediction of hope?  Independence is a long won battle for her and she is now starting to desire a partner.  Someone to wake up with and dance in the living room with.  Someone to call her baby.  Was this picture sent as an invitation?  Oblique and easily ignored, but not by anyone who wanted to be reminded that she was out there.  And she was not just waiting, she sent out this tendril, this invitation.

Who wouldn't be tempted by that smile?

I like to think that the person who received this missive smiled, sighed and packed all their things. Took a train down the coast and knocked on her door just after supper as she was cleaning up.

She came to the door, helped drag the luggage in and they piled it in the corner of the living room.  Maybe the person turned on the radio and still without a word they simply danced together in a peace that is so rarely found.