Jaime was doing it to protect Cersei and their children after Bran witnessed the twins having sex. After Bran woke up, having permanently lost the use of his legs, he couldn't remember what caused his fall. Now he's the Three-Eyed Raven, of course, he's no doubt had a peek at the truth — and by the look on his face, he's ready to confront Jaime about it.
Whatever happens next will be super interesting. Jaime's whole arc has been about his path back to honor and redemption — and a reconciliation with Bran will be crucial for that. BRING ON NEXT WEEK.