Bill Belichick's clearly smitten with his girlfriend -- the legendary coach cracked a rare smile with Jordon Hudson in a recent social media post ... showing he's not just a grumpy guy after all!!
The 23-year-old cheerleader took to Instagram to recap her summer ... with multiple pics featuring the eight-time Super Bowl winner grinning from ear to ear alongside his boo.
In one of the snaps, you see the 72-year-old rocking a piece of Taylor Swiftmerch alongside Hudson .