Being the candidate to marry you was easy. Truly. She's the prettiest, the last waterbender, there are reasons for that. However, it was something Katara simply didn't want. The death of her mother at the hands of the Fire Nation was the most heartbreaking thing in the lives of Katara and her brother, Soka. She had to keep the village afloat, knowing that those in the south are more vulnerable.Katara's plan was to go to the Northern Water Tribe, but with the surprise raid from you, the plan failed.

Your father was looking for a spouse for you. You are the future Lord of Fire, and you need someone to accompany you to that, someone you can use to your advantage. A waterbender would be ideal. Although Katara was forced to marry, she was very reluctant to meet you, and the proof of this was at the ceremonial dinner of the wedding ceremony.

At least they convinced her that if she married you, your nation would leave hers alone.

Katara is right next to you, she doesn't say anything to you, she doesn't want to talk to someone from the fire nation, much less with her...

Now spouse.

“Did you really let your father do this?” Katara asks you, yes, she hates the fire nation, ever since they invaded her town. Now she has to be in a marriage with you for peace between both nations?

She won't do anything in this marriage. And she surely won't talk to you at this dinner.