Pro-golfer Tiger Woods and Olympic ski champ Lindsey Vonn have yet to publicly acknowledge their secret romance and yet, things seem to be getting really serious for the couple.

Not only have the professional athletes been spending lots of time together, but their families are bonding with each other as well. According to US Weekly, Vonn's brother recently gave Woods' two young children, Sam and Charile, ski lessons.

The infamous 37-year-old womanizer met the 28-year-old skier in April 2012, but they didn't become more than friends until November. A number of news outlets including CBS Sports and PEOPLE speculate that they were seeing one another over the last few months.

Earlier this month Vonn suffered a devastating injury during the Alpine World Championships and reportedly returned home to the U.S. on a private jet owned by Woods.

An inside source told PEOPLE that "Tiger and Lindsey have been friends for a while, and nothing started out romantically at all, but they really have a lot in common and got closer and closer. He still refers to her as 'my very good friend,' but he's been spending more and more time talking to her - and talking about her." The sourced added that Vonn isn't bother by Woods' past as a serial cheater who had multiple affairs while he was married to Swedish model Elin Nordegren. "She's not freaked out by his past, and that's really appealing to him," says the source. "He really does deserve to be happy. He has been flogging himself for three years, and it's good to see him moving forward."

After finalizing her divorce last month, Vonn issued a statement in order to head off questions at the world championships. "Lindsey is currently in the midst of the World Cup season in Europe," the statement read. "Her focus is solely on competing and on defending her titles and thus she will not participate in any speculation surrounding her personal life at this time."

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