It's better to have loved Lyrics
I would’ve stayed to clear those final doubts
How suddenly the whole world can change overnight
How suddenly the whole world knows your name
And I’m trying to press the button to rewind
And I find myself whispering ‘There’s more I could have done’
And I wish I had the option to rewind
Is it better to have loved than not at all?
I’m not the same; it feels like I’m missing out
The sky has drained now I must live without
How suddenly the whole world can change overnight
How suddenly the whole world sings your name
And I’m trying to press the button to rewind
And I find myself whispering ‘God, what have you done?’
And I wish I had the option to rewind
Is it better to have loved than not at all?
The subtleties you taught me to admire
And I find myself whispering ‘God, what have you done?’
And I wish I had the option to rewind
Is it better to have loved than not at all?

pretty straightforward. Here he is, broken and shattered after coming to the end of a relationship, and as a result his whole world changes becomes grey, hence: "How suddenly the whole world can change overnight". He wants to go back to the past and undo his wrongs "wish I had the option to rewind". He then questions himself whether experience love was worth feeling the way he does now. this song sings the question that goes through many of our minds.

Admittedly, my first thought was "oh, it's about a breakup". But the opening lyric, "You didn't wait for me to help you out / I would've stayed to clear those final doubts" implies that the -other- person was responsible for what happened. Why would the other person need help, if it was just a breakup? And the lyric, "I find myself thinking, 'God what have you done?'" isn't necessarily about the narrator himself...
I do believe this song is about loss - but it resonates more along the lines of what you'd say to someone who committed suicide. Someone you loved, and will never have in your life again, because you said too many things to push them away, didn't help them, even while thinking things like "There's more I could have done," but knowing it's too late. There's no hope in the song, because the person could never come back, so the only option is to "rewind".
That's the impression it left on me.