The rise of the rom-com sitcom really makes you long for the days of shows about nothing.

In recent years, we have seen a surprising number of failed sitcoms built on the same basic premise: A man and a woman meet, undergo a series of romantic mishaps, and, finally, end up with each other anyway. At its worst, that means awkward gender stereotypes and dates gone wrong (ABC's quickly canceled Manhattan Love Story); at best, it's a generally well-liked series that drags out a love story for way too long (How I Met Your Mother).

But good or bad, these rom-com sitcoms show that the romantic comedy tropes that work so well in a film are an uneasy fit for television.

As my colleague Sarah Eberspacher recently pointed out, romantic comedies work because they serve as a form of escapism. People watch romantic comedies because they're a fun way to forget about reality for a couple of hours: a couple with chemistry, a series of misadventures, and a happy ending, in a tidy little package. But when that formula is converted into television shows — which, if all goes well, last for many seasons — it's hard to sustain the magic. The ridiculousness of the artifice becomes more apparent, and the stories tend to recycle themselves as the show shoulders on.

The most obvious failure of the rom-com sitcom is the way the genre stunts character development. If the leads meet-cute in the pilot episode, every subsequent episode teases the possibility that they'll finally get together. Once they do, the story is over — unless you put them through a never-ending string of mishaps and arguments. Romantic comedies work in film because they are designed for a closed arc. A rom-com TV series with no end in sight stretches the format for an absurd and unnatural amount of time — and as a result, the plot is permanently stuck in stasis.

Even shows that aren't specifically centered around romance can suffer. When New Girl united its will-they/won't they couple in its second season, viewers turned away. No matter how great a show's writing may be, viewers will tire of the same romantic comedy tropes. (To its credit, New Girl eventually realized this, and the show has been significantly better since the writers smartly broke Jess and Nick up.)

It's a trap The Mindy Project has also fallen into in its third season. The show managed to keep things fresh for a few episodes after the will-they/won't-they Danny and Mindy started dating. But it has also warped the fundamental premise of the show, which is Mindy's self-development "project" (one that, prior to her relationship with Danny, appeared to have quite a lengthy future). If The Mindy Project actually goes through with the baby plot it's been teasing, its fans aren't likely to be interested in seeing the two doctors fight over child care responsibilities.

That's not to say there can't be successful television shows about the trials of marriage. FX's Married and HBO's Togetherness both successfully depict the highs and lows of long-term relationships. But those shows aren't about finding romance. They're about keeping romance alive, and they always have been — unlike a show like The Office, which eventually saw its romantic subplot overwhelm the workplace comedy.

The most obvious example of a successful rom-com sitcom remains How I Met Your Mother, which ran for nine seasons on CBS. In a series finale that disappointed many, leads Ted and Robin did, in fact, end up with each other. But How I Met Your Mother also laid a a stronger foundation by cleverly making Ted, its protagonist, a huge fixer-upper. Ted was so self-involved — and so clueless in his relationships with women — that it was almost feasible he'd need more than 200 episodes of self-development before he could settle down with Robin.

That's where How I Met Your Mother differs from similar shows like NBC's A to Z or Marry Me. By making its protagonist a cringe-inducing know-it-all, How I Met Your Mother left plenty of room for actual growth across a successful, multi-season run. A to Z's leads, meanwhile, began their story almost sickeningly sweet, kicking off the picture-perfect love story from the first episode — and leading to a swift cancelation.

Despite the flurry of How I Met Your Mother copycats, there are signs that audiences are ready to move on from the rom-com sitcom. Even more innovative shows, like ABC's surprisingly delightful Trophy Wife, couldn't make it more than one season — though it's easy to imagine a box-office rom-com hit about a young, attractive woman navigating relationships with her husband's ex-wives.

Translate a strong rom-com concept into an open-ended sitcom, and the holes begin to show.