The only time this happens to me is when the fic consistently is just not my cup of tea. And I wouldn't say I stop shipping ANYTHING. If I liked it once, I think I like it permanently. But I'll stop looking for fic and art, and fic and art are generally 80 percent of the fun for me, so it really does take the wind out of my sails when it happens.

Prime example: Harry/Hermione. Couldn't care less about the ship wars and the wank. Just didn't like the fic. At all.