Pokémon Gen 5 made me lose quite a bit of passion for the series.
I know they aren't bad games, in fact I like the story in BW most, but I was only able to finish Pokémon White because White 2 was coming out, and I couldn't even finish White 2, I just headed straight to Gen 6.
Thankfully I found Y and Moon more fun, but ever since Gen 5 I never really got into post game anymore.