the Princess Zelda leads his army to the entrance of Gerudo Desert, Looking to talk with Link, the demon King..
in His fortress, She tries to reason with him, and prevent that a war break out between the seven kingdoms, He doesn't want to listen to Her, 
They two fight and She is defeated.
Link asks Her to withdraw her troops, but She refuses, so, seizing the opportunity, Link, in his ambition,
decides, He must take her as his wife, if necessary, force her to it .., so, the kingdom of Hyrule would be His ...
and therefore, the power to win the coming war that is about to be unleashed ..
sorry, i used google translator.. :C