Stories and comments that speak of "growing distance" between the couple have appeared on social media sites such as Twitter. There have even been unconfirmed reports that the royal palace would release a statement on Friday concerning the couple's relationship.
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HELLO! Online contacted the palace about the reports, and were told: "We don't comment on rumours." Furthermore, the couple's spokeperson confirmed that "there will be no press release of any sort", concerning the couple.
Rumours of a split first began in October, when it was announced Mette-Marit would be taking some time off official duties for sick leave.
Earlier this month the princess underwent neck surgery in Oslo for an ongoing neck problem, spending a few days in a hospital in the capital for the operation on her herniated disc.
The 40-year-old, pictured above with her and Haakon's children Princess Ingrid and Prince Sverre Magnus, then had to enter a rehabilitation programme.
As a result she had to cancel a visit to Atlanta in the US after pulling out of a trip to Finland in October – meaning Prince Haakon went alone.
Since then, the blonde royal has not undertaken any official duties, and she is expected to be out of action until after Christmas.
The last time she was seen in public was on 2 October, when she joined her husband at a lunch in honour of the Netherlands's King Willem-Alexander and Queen Maxima at the Royal Palace of Oslo.