The primary challenge lies not in creating obstacles to keep the couple apart, but in convincing the audience that these two people truly do belong together.
The current box office hit that you're not supposed to like - because it's an Adam Sandler movie - is nobody's idea of a great romantic comedy. In fact, due to its derivative pedigree (based on a movie based on a play based on a French play, no less), the project sounds more like the "xerox of a xerox of a copy of a movie" decried by this sobering screed that's lately been giving Hollywood screenwriters insomnia.
So sue me, but I found parts of it to be LOL funny, despite the usual trademark Sandler homophobia, racism and misogyny, and in terms of What America's In the Mood For right now, I totally get why it's doing well. It's a tan-bodied, creamy, candy-colored bright shiny object of a movie that's just sharp enough, at moments, to transcend its retro stupidity and revel in entertaining Guilty Pleasure silliness. It's also the best thing Jennifer Aniston's done in... well, it's nice to see her in something watchable.
But this is not why I'm writing about - what was the name of it, again? I simply want to point out one particular thing that the movie gets right. [Note: Big SPOILER coming up here, but if you're worried about spoilers in an Adam Sandler comedy, I'm worried about you.] The movie, after a prologue, spends what might seem to some like an inordinate amount of time setting up the deal between Adam and Jen: he's a successful L.A. plastic surgeon, and she's his girl Friday, and clearly - this is where a whole lot of first act leisurely exposition and gags go by - they really enjoy working together.
These two share a sense of humor, they have a rhythm, a wry, screwball-esque give and take; it's fun to hang out with them because they get each other. Even when they're at odds, especially when they're giving each other shit, they make a delightful pair. And that's why, at the later crucial turn of the plot that leads to the inevitable happy ending that you had to expect, given that they're the stars of this romantic comedy (and all-body Brooklyn Decker, despite the trailer, is not)... you believe it: you buy that Adam would choose love over lust, and that he and Jennifer are ultimately the best fit.
Romantic comedy writers all too often put way too much emphasis on figuring out ways to keep their leads apart. But conflicts and obstacles are actually the easy part of romantic comedy screenwriting. The harder task lies in creating what I call a chemical equation for your protagonists - presenting the clear, vivid and genuinely convincing evidence that because he's like this and she's like that, they absolutely, positively must end up a couple. My point isn't that Sandler and Aniston have great chemistry as performers (though they do), it's that the chemistry is on the screenplay page.
Check out the rom-com classic couples that endure (say, Alvy and Annie in Annie Hall, Loretta and Ronnie in Moonstruck, or Harry and Sally in When...) and you'll see that chemical equation writ large. We root for them, and we love them, because they're fully developed characters who have just the right quirky pieces between them to perfectly complete a romantic puzzle. Which is why the obstacles that do come between them pack so much heat - and humor.
I'm not suggesting that Danny and Katherine in Just Go With It are one for the ages. But if you'd like to see an object lesson in how to make an audience buy into any rom-com's most vital buy, check out the smoothly engineered chemical combustion that gets this movie over its blatant contrivances. You may find yourself laughing at the sort of set pieces that'll make you hate yourself in the morning, but hey - I'll bet you've blown a few bucks on far more egregious yucks.