He died before the wedding. That was who Edmure was shooting flaming arrows at floating down the river.
See, this is why I'm currently rewatching GoT. When I originally watched GoT for the first time back in December, I knew very little about it. So a lot of details & scenes on the show & references to stuff that took place before the show/books went over my head & I didn't understand some things. This forum & especially the ASOFAI wiki site has been helpful. I done basically read every notable character's backstory & storylines from the Book 1 & 2 and other stuff.
Now that I'm rewatching Season 1, I'm able to pick up & understand
ALL the details & references that went over my head the first time I watched it. For example:
1. I didn't realize that The Hound's older brother The Mountain was on this show.
2. I didn't realize how cold Catlyn was to Jon Snow in the first couple of episodes.
3. I didn't quite understand that whenever a character is telling a random story on the show, they're talking about the back history that takes place before the show/books.
4. I confused Lancel Lannister with Loras Tyrell (Probably because Lancel dress liked a flamboyant fakkit). I thought Lancel was the dude that shaved Renley's chest & went down on him.
5. I didn't know the difference between the King's Guard, The City Watch/Goldcloaks, & the Lannister's own Guards.
6. Theon is basically a glorified servant in the Stark Household, despite being a Ward. I didn't know folks were making fun of him for being a prisoner.
7. Jory Cassel is a notable character
That's some of them off the top of my head.