The 43-year-old singer and the Bush frontman wed in 2002, and are parents to two sons, Kingston and Zuma.
Earlier this month, the couple were spotted leaving a therapy session looking visibly upset.
'Over the past two years they've spent less and less time together,' News.com.au quoted a source as telling In Touch magazine.
The trouble is attributed to Rossdale's hectic tour schedule.
The time he spends away from home performing with alternative rock band Bush is said to be having a massive impact on the couple's relationship.
'They used to be affectionate with each other and laugh a lot,' an insider said. 'That never happens anymore.'
Photograph: Lucy Nicholson/Reuters
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