The meaning of "wrote her off"

[kjc0123]

What is the meaning of "wrote her off" in the following sentences?

 

He had decided to have dinner with Kaley before he went South for a while, and before she technically became a former student. Exams were over, what was the harm? She would be around for the summer and he was determined to pursue her, with great caution. Caution because that's what every female got from him. Caution because he thought he saw potential in this one.
But the first phone call to her number was a disaster. A male voice answered, a younger voice, Ray thought, and whoever he was, he wasn't too pleased that Ray had called. When Kaley got on the phone she was abrupt. Ray asked if he could call at a better time. She said no, she'd ring him back. 
He waited three days then wrote her off, something he could do as easily as flipping the calendar to the next month. 

[Ouisch]

He gave up hope of ever hearing from her or seeing her again.  He decided to totally forget about her.

[jno]

It's a commercial term - if you 'write off' your car in an accident you damage it so badly you can't repair it; if you write off some entry in your company's accounts, you acknowledge that you won't get your money back and won't waste any more money trying to do so.

[epicure_2002]

"wrote her off" in this case is an expression which means no longer being considered.
in this case kaley is no longer being considered by ray as worthy of his time and attention.