Travis Kelce may have lost to the Buffalo Bills Sunday ... but he's still a big winner in the eyes of his superstar girlfriend, Taylor Swift, who planted a passionate kiss on his cheek at the game!!!

Check out this photo ... Taylor closes her eyes as she holds Travis' head with both hands and delivers some major lip service to the side of his grinning face. Travis is one lucky guy, indeed!!!

The happy couple was snapped at a festive Christmas-themed bar for a postgame party after the K.C. Chiefs battled the Bills at Arrowhead Stadium Sunday.

Celeb stylist Patrick Regan uploaded the snap to his Instagram page Monday, along with a bunch of other pics from the Bills 20-17 victory over the Chiefs.

As you know, Taylor showed up again to the stadium to cheer on Travis as the hunky tight end recorded 6 catches for 83 yards. Not too shabby!

In fact, it was the sixth time the pop star popped up on gameday for Travis -- and, for those who are keeping count, the Chiefs have a 4-2 winning record with Taylor watching from the crowd.