Christian McCaffrey just got an AWESOME 25th birthday present -- a love note from one of the hottest women on the planet -- and it's adorable!!!
Olivia Culpo penned the mush on Monday afternoon ... gushing over her NFL superstar boyfriend with a series of pictures and sweet words.
"I’m obsessed with you ud83dude0d," Culpo said of her man on her social media page. "Happy birthday kintin!!!!!!! Thank you for making me the luckiest girl in the world I love you."
Christian didn't wait long to respond .