Deshaun Watson took some time off from preparing for the Buffalo Bills on Wednesday to celebrate his smokin' hot model GF's birthday ... and we gotta say, dude is MVP caliber on AND off the field!!

The Houston Texans superstar hit up a fancy dinner with Jilly Anais -- a legendary Instagram model -- and he brought diamonds and a custom Louis Vuitton box for the occasion.

Seems Jilly, who turned 24 this week, loved the gifts ... 'cause she couldn't stop showin' them off -- and the two even exchanged L-bombs afterward! AWWWW!!!

Of course, it's a massive week for Watson ... the 24-year-old QB is set to play in his second-ever NFL playoff game this weekend -- so Jilly MUST be pretty special to the guy!

And, if ya watch the clips ... it ain't hard to get a read on that -- 'cause pics of Watson and Jilly were laid out all over the birthday table!!

As for the rest of the party ... backup QB AJ McCarron's wife, Katherine Webb, was there -- and she posted video of Watson and Jilly kissing, saying "We love you!"