Yeah, but why "unfaithful" red-ellie? There is no signs/no word of that. Of course that does not exclude this "unfaithful" theory. I'd say she is simply leaving him - cause perhaps she's now looking for "real love" and not just "eternal right" of receiving love. Yeah, maybe she found her love.
Actually it's not said anywhere that maybe he dumps her. As I know this is about Blunts personal life and he is just interpreting what he has done to some girl. But as J. Blunt has stated this song is very heart-rending to him and so he should then be feeling guilty and not stating a question of that. But the song might be a way of making himself feel better thus - he makes a question.
But this is just a small theory.
Jkbwolf wrote that "he"(J. Blunt himself I assume) had been divorced by his wife. If that is true then it's all much clearer to me.
Any thoughts anyone?