Pairing: Jaina Solo/Jagged Fel
Fic Title: The Changing Tides Trilogy: Devotion, Serenity and Revelation
Link: http://www.rmff.net/books/devotion.htm ; http://www.rmff.net/books/serenity.htm ; http://boards.theforce.net/fan_fiction_stories_classic_jc_board_reply_only/b10016/7590982/p1
Rating/Warning(s): Possibly PG-13?
Why This Must Be Read:
Nowadays Jedi-Princess-Solo prefers Jaina/Kyp, but a few years back, she was known as one of the best writers of Jaina/Jag fics in the fandom, and with good reason. This trilogy is set during the Yuuzhan Vong invasion, and is definitely something that anyone who likes Jaina Solo and Jag Fel together should check out. They're all very long fics.
I'm afraid that as far as I'm aware, the third story, Revelation, was only ever posted in a forum, so you do have to scroll past people's comments to get to each chapter. I've searched for an archived version of it, but unfortunately I can't find one.