I cried and cried at the end of season 3 (even if that season was just poorly thought out filler...) simply because I was sad that I wouldn't have any new material to see the characters in and would miss them, :c . It's one of the few series where I actually enjoyed almost all of the main characters~
I went on to read the manga because I heard it ended differently, and I must say, I was a lot happier with that ending than the anime one!