Despite the disasterous way in which Tyrion’s marriage to Tysha ended, Tyrion has always believed that Jaime procured her and set the scene of her being chased by brigands as a kindness to him, and he loved his elder brother because of that.  However, Jaime tells him, "She [Tysha] was no whore. I never bought her for you. That was a lie Father commanded me to tell." (III: 873)