Tiger Woods & Lindsey Vonn

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 Meyers" and admitted she hates golf.

Here's Lindsey Vonn, Olympic gold medal skier and girlfriend of Tiger Woods, appearing Monday on "Late Night with Seth Meyers" -- and Tiger's ex-wife, Elin Nordegren, seen a few years back strolling on Miami Beach.

The question is ...

It's shocking enough to see Tiger Woods hanging out with his ex-wife Elin Nordegren again ... but even MORE SHOCKING to see them together with Tiger's GF Lindsey Vonn by his side.

Lindsey Vonn has gone from the boring (taking Tiger Woods' kids to school) to the SUPER FUN ... jet skiing with Tiger and his little ones in Palm Beach yesterday.

The new couple decided to take advantage of the long weekend by hitting the water with the kids near Tiger's Florida home.

One day after Lindsey Vonn was spotted playing mom by dropping off his kids with Elin Nordegren at school alone, Tiger Woods joined in on the child-rearing fun.

Looking like one big happy family, Tiger and Lindsey -- who have been dating for around 5 to 6 months -- made the early morning trek to drop off his adorable children at their Palm Beach school on Tuesday.

Lindsey Vonn might be in it with Tiger Woods for the long haul ... because she was spotted this morning taking his kids to school ... with no sign of Tiger.

The two awkwardly announced their relationship via Facebook back in March, saying they have "been friends for some time, but over the last few months we have become very close and are now dating."

Tiger Woods lost the shirt off his back ... and this time his ex-wife Elin Nordegren had nothing to do with it.

The 37-year-old golf star aired out his man nipples and soaked up the sun by going shirtless on his yacht in Palm Beach on Tuesday.

While his fancy schmancy boat is called Solitude, Tiger spent the afternoon lounging and fishing with his two adorable kids and his sexy bikini-clad girlfriend Lindsey Vonn yesterday.

Tiger Woods and Lindsey Vonn made their relationship red carpet official ... by holding hands at the Costume Institute Gala in NYC on Monday.

This is the sports super couple's first public display of affection since revealing they were bangin' by posting cheesy pics together on Facebook back in March.

In a glimpse of what may lie in their near future, Lindsey wore a virginal white gown as they walked down an aisle together.

Ironically, Tiger's next gig is competing in The Players Championship ... something he knows all about.

Might as well tailor that green jacket for Tiger Woods ... 'cause his 5'10" blonde good luck piece -- aka Lindsey Vonn -- showed up for round one of The Masters.

LV turned up at Augusta National to support her man wearing a giant floppy hat ... perhaps to make sure cameras can find her all day while she follows Tiger?

We're betting Tiger doesn't care what she wears 'cause he's been on a tear since going public about banging Lindsey -- winning two tournaments in a row, and 3 out of his last 5.

Now that he's confirmed he's dating 28-year-old Olympic skier Lindsey Vonn, Tiger Woods has his choice of rooms to make the magic happen in his sick $60 million mega estate.

Tiger's ridiculous waterfront crib on Florida's exclusive Jupiter Island comes with all the bare necessities for an athletic super couple to work up a sweat together ... like a tennis court, diving pool and lap pool, running track, boat slip and the ubiquitous backyard golf course.

Lindsey will no doubt enjoy her time being the mistress of the house.

Once a cheater, always a cheater ... so says a former Tiger Woods mistress who tells TMZ Tiger's new GF Lindsey Vonn better know what she's getting herself into.

We spoke to former hooker/porn star/ Devon James -- who tells us she was shocked when she saw the pics of Tiger and Lindsey on Facebook yesterday ... saying, "I thought he would have picked a woman who was more petite and not someone who is more muscular and has a bigger head than his."

James continues, "But maybe his taste has changed since Elin and the 27 mistresses."

"But you know when the pics came out of Tiger and his new girlfriend ... somewhere, 15 other girls were going , 'Huh? I thought I was his GF!'"

Tiger Woods and Lindsey Vonn just admitted what we've all known for weeks -- they are dating ... and they've already posed for the kind of cheesy couple photos normally reserved for people about to get married.

Tiger and Lindsey each posted the dating confession on their Twitter and Facebook pages. Tiger's said ... "Something nice that's happened off the course was meeting Lindsey Vonn. Lindsey and I have been friends for some time, but over the last few months we have become very close and are now dating."

Lindsey posted a very similar comment ... "Our relationship evolved from a friendship into something more over these past few months and it has made me very happy."

But the best part of their coming out is definitely the corny photo shoot.