It clicks now, The Doctor was saying “spoilers” to reference RIVER. River is the one who changed him, and changed his perspective. She showed him and confronted him about what his regret and anger was turning him into. She taught 11 how to love. Rose handled 9 and 10, but 11’s true match was River. She protected him, and for all we know, she even helped him devise the idea to save Gallifrey. She helped him move past the monsters of his past, to avoid becoming a monster himself. 11 moved on, and River, his wife, the child of the TARDIS, and a TARDIS-made Time Lord, was why.