Keira Knightley's Ex Writes Song About Her.KEIRA KNIGHTLEY's former lover JAMIE DORNAN has cashed in on their romance by writing a song about the British actress.The Irish model enjoyed a two-year romance with the PRIDE & PREJUDICE beauty, but bailed when her escalating fame put pressure on the relationship.He says, "The song hurts so much when I sing it. I'm in so much pain afterwards."It's about the difficult times in a relationship, everyone has them - I still speak to Keira, we were so in love."Of his failed relationship with Knightley he says, "I was intimidated by certain things that came with her fame and I began to feel out of my depth."It's still hard to talk about".