Nicole Kidman 's filing for Portuguese citizenship is the "clearest sign yet" her 19-year marriage to Keith Urban is in serious trouble, sources tell RadarOnline.com .

"It's no secret they've juggled long-distance for years, but going ahead to Portugal without Keith is a bold signal things are not good between them," a source close to the actress told us.

"It's like she's set on building a whole other life in Europe – and he will not be part of it." Article continues below advertisement

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The actress' application, lodged with Portugal's Agency for Integration, Migration and Asylum, included only her name and not that of Urban, 57, who remains in Nashville.

Kidma

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