I have had three.
One my husband died the morning after in a dramatic duel to the death? It was also a secret and and the ensuing baby drama was interesting and a massive dramatic train wreck. But married for the possibility of owning a town - was not a bad gamble on a L&L game. My sworn knights were super awesome afterwards too @Meg
Another I apped in already married with a very good friend and often rp buddy. It was really interesting to play out that long term relationship and gave them a very different sort of rapport since they were still crazy about each other. They got remarried in space after fighting aliens. Obnoxiously.
The third was actually also played with the same friend, but they apped in as my NPC hubs after a plotted kidnapping. It was a total arranged marriage and a mix of chilly and mutual respect. So my experience has been that it you like and trust the other player it can be loads of fun! But also don't get hitched the night before a duel. (Or do. Idk)