Broken Strings Sing A Long

What do you think of this song? Do you think "but you broke me" refers to her cheating on him? To me, the rest of the song seems like they were once in love, but lost the fire for each other. Anything to add?

On it tears me up

Oh it tears me up
I try to hold on, but it hurts too much
I try to forgive, but it's not enough to make it all okay

You can't play on broken strings
You can't feel anything that your heart don't want to feel
I can't tell you something that ain't real

Oh the truth hurts
And lies worse
How can I give anymore
When I love you a little less than before

"Broken Strings" by James Morrison. Damn. This sounds too nice to be a breakup song. The above was the only bit I remembered.