Egils saga (chs 32-5) tells of a young man from Sogn in western Norway, Björn, described as a great traveller, 'sometimes on Viking raids, and sometimes on trading voyages', and a very capable man. He falls in love at a party, as one does, with a beautiful girl, Þóra Lace-sleeve, and abducts her from her home while her brother is away. His father, who is friends with her brother, ensures that the two live like brother and sister, but does not insist on sending her back home. In the end, with the connivance of Björn's mother, the young couple elope. On their voyage south, they are shipwrecked on Mousa. They get to hear that the king of Norway wants Björn killed, so they quickly get married then and there, and spend the winter in the broch. They then make off to Iceland, where they end up at Borg, at the farm of Egill's father Skalla-Grímr. The story ends happily enough for the young couple, though there are many further ramifications for the plot, which you'll have to read the saga to find out, if you haven't already!
Although the Orkneyinga saga anecdote is set in a chronologically later period than the Egils saga story, I can't help wondering if the latter is modelled on the former. Orkneyinga saga is an earlier text than Egils saga, and we know that Snorri Sturluson read it (because it is mentioned in Heimskringla). So if he also wrote Egils saga (a big 'if', but certainly not impossible), then he might well have modelled his story of a romantic young couple on that of the slightly less romantic middle-aged couple. Or is it just that Mousa is such a romantic place that it spawned more than one fanciful tale of people's adventures there?