Who is Laura from High Fidelity and what is their importance?

Laura is Rob's girlfriend. Their relationship becomes sour when she finds a job as a lawyer and begins earning more money than him. It becomes worse when she gets pregnant and Rob has an affair. Laura aborts the baby and just about manages to forgive him. He then proceeds to borrow a large sum of money from her that he never pays back. At the beginning of the book, she leaves him and takes up with his old friend Ian Ray.