Αυθεντικό κείμενο - Αγγλικά - My Constant.

There are some points in the text that have to be specified in order to translate it properly:
To whom is it adressed ? A man or a woman?
What do you intend by "you can move on now"?
It seems to be there some sort of contradition (perhaps intentional) between the ideas that implies "constant" and "change/move on".
Is it a break-up message which is meant to be written on a ring?
Sorry for my being somewhat intrusive, but I can't accurately translate this without further explanations...