The royal licenses can be found in the National Archives. Not sure if they're online. Up until 1918 it was necessary to seek royal consent for illegal marriage links (including cousins), and by re-marriage after divorce.
Prince Regent Frederik VI (1784-1808), King of Denmark-Norway (1808-1839) He would have granted their marriage.
Østen Olsen had an attestation from Næs that he was born Nov 1st 1810. The baptismal record is #10, and the parents are recorded as Ole Helgesen and Kari Torchelsdatter, Stavn.
The confirmation record gives the father as Ole Hørjussen, Næs and the mother Kari Torchelsdatter. Østen is said to live on Høelen.