Finding happiness in a heartbreak

Heartbreak causes many tears,
Looking back at memories through the years, 
But that heartbreak can light a spark,
A great big one inside my heart, 
You see,
Because the one that's there for me, 
I realise the last one was just a bit of fun,
Because the one I never thought, 
Is the one who holds the key, 
To my heart,
and I hope he won't let go of me.