Ed Sheeran recently revealed the backstory behind his verse in Taylor Swift's song "End Game." The verse references their collaborations on songs like "Everything Has Changed" and "The Joker And The Queen." Ed clarified that the four words he would never say are "will you marry me," which he said to his now-wife Cherry Seaborn shortly after the song's release. The lyrics of "End Game" now make sense in the context of Ed and Cherry's relationship, which began at a Fourth of July party and led to their marriage and two daughters.
Source: https://www.buzzfeed.com/stephaniesoteriou/ed-sheeran-confirms-taylor-swift-end-game-lyrics-meaning