I liked Chase until the main Marshal Annie let her criminal father go!
I liked The Big Bang Theory until Raj slept with Penny.
I liked The West Wing until Rob Lowe left.
I liked Top Chef Masters until this season’s craziness.
I liked Prison Break up until they started breaking out of prisons the second time, season 3 I believe.
I liked Roswell until Ron Moore killed Alex.
(I kept watching after that, but it wasn’t the same.)
I liked The 4400 until season three, or so, when they seemed to start to get a whole lot more soap opera-ish and less of a supernatural show.
I liked The Unit until they decided the wives needed to be more involved in doing missions.
I lked Pettycoat Junction until Bea Benaderet got sick.
I liked My Three Sons until Mike moved out and they adopted the kid from next door.
I liked Roseanne until Original Blonde Daughter came back and it started getting all meta.
I liked Home Improvement until Jill started losing weight.
I liked Designing Women until the Clarence Thomas hearings turned the characters against each other.
I liked ER until the Dr. Green torture became too much.
I liked Grey’s Anatomy until Izzy stole an organ for her boyfriend and had to sit in the corner for punishment. Still watched until The beginning of season 3 when that whiney bitch Merideth did not drown as promised. That’s when I realized I hated everyone on the show and stopped watching.
I liked Bones until they made Zack an accomplice to a serial killer.
Not arguing against the meat of your complaint here, but you were either watching on a different schedule than me or have gotten the time a bit mixed up:
Izzy stealing the heart and getting what came to her was the end of season 2, beginning of 3.
Meredith nearly drowning was the February sweeps for season 3, a bit over halfway through.
I liked Dallas until JR got shot.
I liked Happy Days until Fonzie jumped the shark.
I liked* Lost in Space* until it went to color.
I liked Alias until SD-6 fell and it became clear the network was not allowing JJ Abrams and others maintain long-term storylines very much.
I liked Babylon 5 until season 5, though I find I can watch the whole show if I cut out about 12 episodes from season 5(no Byron for me, thank you). I blame the near cancellation for it, though.
Exactly what I was going to say except I like it until they broke in to prison in season 2.
I liked South Park until Mr. Slave and Lemmewinks.
Oh, and my wife and I, both of whom have a high tolerance for sticking with shows, liked **X-files **until Mulder left. Even with his appearances in the last two seasons, it just was not enough.
Your chronology works as well as mine. Wasn’t there a long wait between Meredeth jumping into the river and her not drowning?
Millennium until they wimped out on the “epidemic wipes out the 90% of Earth’s population” Season 2 cliffhanger.
X-Files until…well, at some point it just got silly. I think the final straw was that “All Your Questions Will Be Answered” episode (or set of episodes) that ended up doing nothing of sort.
Grounded for Life until they stopped producing episodes on film and the tone of the show changed for semi-edgy to ABC Family level comedy.
I liked Lost until they opened the hatch.
I liked 24 until the cougar attacked Jack’s daughter.
I liked The Event until Sophia became a soap opera villain.
In all fairness, Raj and Penny might have been in bed together, but we do not know if they “slept” together. In the Biblical sense.
And what if they did? True, it might be a “jump the shark”, but we have about 5 minutes of writing after the “coitus”. Not sure if anyone should damn the show because of this moment, yet.
I liked Cheers until Dianne left. Hated neurotic Rebecca.
I liked All in the Family until Mike and Gloria moved next door.