The writing for Klaine is so absurd that only true diehards are still excited by any of this.
Let's recap.
Kurt and Blaine meet cute. They become friends, hang out, act flirty, do a cute Christmas duet, and spend a few episodes having a semi-natural slow progression of friendship with budding romantic undertones.
Meanwhile, "Klaine" builds up into such a "thing" that Ryan Murphy decides he wants to draw out the will-they-or-won't-they "suspense" and tries to turn the identity of Kurt's boyfriend into some "mystery" even though he never ever introduces any viable candidate other than Blaine.
Suddenly, out of nowhere, Blaine has a crush on random Gap guy, and later sticks his tongue down Rachel's throat in a series of manufactured roadblocks.
After a harsh spat about Rachel and Blaine being bi-curious for a hot minute, voila, this whole pointless manufactured mini-conflict is resolved offscreen and Klaine are BFF again.
After spending major subplots of two episodes friendzoning Kurt in degrading and embarrassing ways, Blaine suddenly realizes he's madly in love with Kurt after watching Kurt sing about a dead bird. It's a ridiculous catalyst, but "The Scene" is cute enough that everyone is forgiving.
For a while, basically the rest of Season 2 and the entirety of Season 3, Klaine is a pretty stable couple, with scattered one-episode drama. Although Blaine devolves into a clingy dork who follows Kurt around like a lovesick puppy dog or a victim of a Harry Potter love potion.
Then the writers start really going haywire with everything.
After talking up how interesting it's gonna be to "portray a long-distance relationship", they have Blaine fall into bed with random Facebook (*cough*Grindr*cough*) lighthouse boy like 5 minutes after Kurt moves to New York. Blaine flies to New York, has hysterical meltdown while trying to sing Teenage Dream, confessions and breakup songs and angst galore.
Blaine spends the next few episodes roaming the halls melodramatically weeping while we don't get much of Kurt's POV about any of this.
Now things really start to get whiplashy.
Klaine has a well-done Thanksgiving phone call conversation where Kurt says he wants to have a heart-to-heart over Christmas.
But the writers have forgotten this by next episode, as Kurt has no intention of seeing Blaine until Burt shoves them into each other's arms for Christmas.
After spending 2 episodes putting Klaine in a gradual drift back toward each other, suddenly bam out of nowhere, Blaine wants a piece of White Chocolate (a.k.a. Sam) and Kurt is dating Adam, a laughably blatantly irrevelant "midgame love interest" whom the writers never even try to take seriously.
Then, BAM. With no lead-in whatsoever, Klaine are suddenly making out in the backseat of a car and having hotel room sex. Blaine is unshakably convinced they are getting back together. But by next episode he's in love with Sam again.
Blaine whiplashes back and forth between pining for Kurt and singing Phil Collins love songs to Sam, while Kurt is more devoted to his boyfriend pillow than to Adam.
Now, hold on to your butts, 'cause this is where the writers officially just hit the pedal off a cliff.
After spending half the season pining after Sam, Blaine whiplashes back into his "Kurt is my soulmate, and we're gonna be together forever and ever!" default setting, and decides to propose to his ex-boyfriend (?!).
Writers make a season "cliffhanger" out of this and in a sad delusion, seem to believe the suspense has viewers riveted to the edge of their seats.
First episode of Season 5, possibly due to the death of Cory Monteith and Finchel being as irrevocably kaput as a ship can possibly be, though possibly also just because they have no idea where they were even going with any of this, the writers decide to slap their second most popular ship back together ASAP, waving away a season of angst and slapping Klaine back together in 2 minutes, basically making the ENTIRE SEASON OF KLAINE ANGST completely pointless, especially as neither of them grew from the experience. In fact, if anything, Blaine regressed and is clingier than ever.
Blaine forges onward with his absurd proposal idea, and Kurt says yes, meaning Klaine is broken up for months, gets back together, and thinks it's an awesome idea to get engaged like 5 minutes later.
Nothing much else happens until Blaine gets to New York. Klaine has some of the most adult, complex, and realistic relationship drama about the difficulties of cohabiting Glee has ever done. Unfortunately, the writers beat the dead horse into glue, spending major screentime of several consecutive episodes making Blaine desperately co-dependent, insecure, clingy, and needy, and repeating the same arc of working himself into a hysterical meltdown and being reassured every single episode as if his counter gets reset every morning.
After affirming their eternal love for like, the 10,000th time and ending the season in each other's arms....sometime over the summer, Klaine breaks up (again) and Blaine starts dating Karofsky, of all possible people on Earth.
Blaine is with Karofsky for probably at least 4 out of 13 episodes.
But fear not! Klaine gets married before the end of the season...basically making their 100th breakup just as utterly pointless a waste of time as the rest.
"Do you hear that, Mr. Anderson? That is the sound of inevitability..."
