It's a very light, fluffy, 'chick-lit', rom com.
All I can remember is that a couple break up and she ends up in a whirlwind romance with the lead singer of a band and regrets it. Her ex I think was something to do with the lighting for the band's show.
Pretty sure it's by someone like Lindsey Kelk, Giovanna Fletcher or similar but none of the synopsis of their books rings a bell.
No idea why it's stuck in my head but if anyone recognises it please put me out of my misery!