The singer was photographed after the game Sunday next to her man, posing with Chiefs wide receiver Mecole Hardman Jr. and his girlfriend, Chariah Gordon. In one of the shots, you can see TayTay kissing Travis on the cheek, with her hand on his chest.

Like we said, this marks the debut of any kind of affection at this level -- thus far, we've only seen them hold hands in public ... so, it would seem their PDA is growing by the day.

TBH, this is a side of Taylor we haven't really seen until now. Before getting with Travis, she's tended to be quite private and away from the spotlight as it relates to her significant others ... particularly while she was dating Joe Alwyn. They were practically in the shadows.

Now, however, Taylor seems to be embracing the public nature of this relationship ... and she's loving it. Not only have we seen her express herself at games full throttle, but even when it comes to stuff like this -- it doesn't seem like she and Trav are all that shy.

As for TK ... he, too, seems ready for all the scrutiny -- something that undoubtedly comes with the territory of what he does professionally. If anything, this attention is nothing new.

Gotta say, the more we see of these two ... the more it feels like they could have real legs as a couple. Their lives are certainly blending at a fast rate -- and the people are all about it.