Plan B

Plan B is a Argentinean comedy-drama film by writer-director Marco Berger. Bruno, a young bohemian living in Buenos Aires, learns that his ex-girlfriend Laura is happily with a photographer named Pablo and becomes jealous enough to begin searching for ways to win her back. When he discovers that Pablo is bisexual, he hatches a "Plan B" to make him break up with Laura: seduce him. Entanglements and complications ensue.

Tropes used in Plan B include:

A Simple Plan: Win your girlfriend back by seducing her new boyfriend? What Could Possibly Go Wrong?
Becoming the Mask: While initially only trying to win over Pablo just to steal back his ex-girlfriend, Bruno ends up genuinely infatuated with him.
Bi the Way: Pablo. It turns out he was lying, however, and his feelings for Bruno are more of a case of If It's You It's Okay.
Closet Key: Bruno tries to be this to Pablo. Turns out they are for each other.
Erudite Stoner: Bruno and Pablo have shades of this.
Faux Yay: Bruno's entire scheme hinges on this. Things go pear-shaped when he realizes that it became not so faux somewhere along the way.
Gay Bravado: Bruno and Pablo's flirtations with each other are initially done in a jokey, "hey let's show just how macho we are for not freaking out about being called fags" manner. They become distinctly less macho later on, with Pablo freaking out when he tries to call Bruno's bluff by having sex with him and Bruno vomiting when his friend points out that it's clear that he's in love with Pablo. The director has said that this is a reflection of Argentinean culture where two guys sleeping next to each other in their underwear is considered a display of masculinity but actual homosexuality gives them more pause.
Gayngst: It's subtler than in many other queer films due to the film focusing more on the general (b)romance than a Coming Out Story, but definitely there.
Gone Horribly Right: Bruno succeeds in making Pablo sexually confused enough to dump Laura...and making himself sexually confused too and unable to take up Laura's offer to get back together due to the Faux Yay having become very real between him and Pablo.
Green-Eyed Monster: Contrary to the most commonly-given film summary of Laura dumping Bruno, Bruno was actually the one who ended things between them because he was bored, but seeing her being happy with Pablo makes him jealous enough to revive his attempts to win her back. Laura even points out that he's doing this more out of wounded pride than any actual feelings for her.
Have I Mentioned I Am Heterosexual Today?: Even when Bruno tries to get Pablo to kiss him again while sober with the lamest-sounding excuse in the world, he feels the need to clarify that he's Not Gay and Pablo repeatedly insists that he's Not Gay either.
Hilarity Ensues: Noticeably averted, with a "pretend to be gay to have a guy dump your ex-girlfriend" plan that seems ripe for a Crazy Enough to Work Zany Scheme comedy being used instead to set up a surprisingly insightful exploration of two people gradually discovering that love can work in the strangest of ways.
If It's You It's Okay
Kissing Under the Influence: Bruno and Pablo's first kiss occurs when they're really, really drunk and being egged on by their female friend to keep up their Gay Bravado.
Leave the Camera Running: There are several extended shots of the scenery and characters' faces.
Mistaken for Gay: Pablo stares at Bruno so openly during their first encounter in the gym that it drives Bruno to check with a friend to see if Pablo's gay, except that it turns out that Pablo was just confused by how much Bruno resembled a certain "French man" in one of Laura's photos. Or was he? He did keep a photo of Bruno in his wallet and all...
Precious Photo: Pablo reveals to Bruno at the end that he keeps a photo of him in his wallet. And it isn't just any random photo either -- it's a photo of Bruno holding a kitten from way back at the beginning of the film from when he and Pablo hadn't even met properly yet and Pablo was seemingly secure in his heterosexual relationship with Laura, which strongly implies that Pablo has been interested in Bruno for a lot longer than Bruno and the audience thought, especially since he loses the wallet early on before Bruno really ramps up the seduction attempts.
Relationship Sabotage: Bruno tries to do this to Pablo and Laura in a very roundabout way. It works, but by then it's not Laura he wants to be with.
Time for Plan B
Triang Relations: Type 6 with Bruno at A and Pablo and Laura at B and C. It ultimately ends with Laura at A and Bruno and Pablo at B and C.
Unkempt Beauty: Bruno and Pablo might not be model-gorgeous and actually have hair on their faces and bodies, but they're still pretty easy on the eyes overall, especially when wearing nothing but their underwear in bed.
Why Can't I Hate You?: While not explicitly stated by Bruno, it's clear that he likes his ex's boyfriend a lot more than he expected to.
Will They or Won't They?: Will Bruno and Laura get back together? Of course, this proves to be a bait-and-switch question with the real question being "Will Bruno and Pablo take that final step from bromance to romance?"
Your Cheating Heart: Throughout the entire film, Laura has been cheating on Pablo with Bruno behind his back.