Chalk up another loss for Tiger Woods ... this time, it's his girlfriend -- 'cause Lindsey Vonn just announced the couple has officially broken up.
The world champion skier broke the news on Facebook ... saying, "After nearly three years together, Tiger and I have mutually decided to end our relationship."
"I will always cherish the memories that we've created together. Unfortunately, we both lead incredibly hectic lives that force us to spend a majority of our time apart."
"I will always admire and respect Tiger. He and his beautiful family will always hold a special place in my heart."
Probably for the best ... since she just went on "Late Night with Seth Myers" and admitted she hates golf.