Comments of chapter undefined of A Walk Among Stars

I can see where the confusion comes from as it really isn't explained at all but the subtext is basically a power imbalance. The Lauragne's hold more power than Gabriel's family. This means that say, like a year before this happens, one of the Lauragne's, it could be any noble family too, came and saw how Gabriel could heal all of these wounds with a touch. So they report back and find more information which then leads to the much more powerful family pressuring Gabriel's family into sending him off to be married to their family because they want that asset for their own. That would be the carrot. As for why they just didn't refuse, or why word wouldn't have spread. To address why word didn't spread is becuase cities, especially in an era like this, are very isolated with people rarely, if ever having contact with any other city. This means that word wouldn't spread. As for the former, it would be because Gabriel's family couldn't refuse, they would be destroyed by the superior political power of the Lauragnes and as such it would be more beneficial to send him there rather than to defy and risk destruction. It wasn't too hard of a choice either because they already have an heir in Gabriel's sister. I hope that makes sense. And I do admit that I should have explained that but its a bit too late.