Travis Kelce's Kansas City Chiefs teammates' jaws were on the floor when they realized he was REALLY dating Taylor Swift ... with Chris Jones and Patrick Mahomes admitting they were stunned when the pop superstar showed up to her first game.
The topic came up in the new "The Kingdom" documentary that dropped on Thursday ... which broke down the Pro Bowl tight end's journey from publicly shooting his shot on his "New Heights" podcast to landing a full-on relationship with the musician.