They weren't quite married, but "Le Divorce" star Naomi Watts has done just that -- splitting up with fellow attractive Aussie Heath Ledger, his sister, Australian publicist Kate Ledger, confirms to Melbourne's Herald Sun newspaper.

"Heath Ledger and Naomi Watts have made the decision to go their separate ways," her statement reads. "At this time in their lives both are busy pursuing careers which are taking them in different directions. They remain close friends."

Ledger, 24, and Watts, 35, met on the set of "Ned Kelly" last year and were together for 16 months. Reports that the romance was on the rocks were flatly denied last February, when the rumors started circulating.

Kate Ledger would not reveal when the couple parted, but the Herald Sun, saying that it took place a month ago, termed the split amicable.

Heath Ledger is now in Prague filming director Terry Gilliam's "The Brothers Grimm," costarring Matt Damon, while Watts has occasionally been seen making the social rounds in Manhattan, where she is currently making the thriller "Stay," with Ewan McGregor.

Meanwhile, in other domestic news closer to home, David Letterman, 56, reportedly married in secret longtime girlfriend, Regina Lasko, at his Montana ranch a few weekends ago, claims MSNBC. Lasko, 42, is six months pregnant with Letterman's child.

A spokesman for the "Late Night" host would only tell the news Web site: "My comment is we never comment on Dave's private life."