In Battle of Britain this is a Deconstructed and possibly Unbuilt Trope. Colin is opposed to Maggie serving in uniform and would prefer her to be at home, out of harm's way. Maggie feels driven by duty and tries to get him to understand why she insists. Rather than bonding over war, it's a constant source of stress and a strain on their marriage.
Tony Stark aka Iron Man and Pepper Potts have always been on the cusp of this, with Iron Man 3Final Battle where Tony and Pepper killing the Big Bad being the most prominent instance. UntilAvengers: Endgame where Pepper has own Powered Armour and she and Tony at one point gloriously twirl around each other shooting lasers and missiles as one, it's just beautiful.
Peter Quill aka Starlord and Gamora from the Guardians of the Galaxy movies team up frequently, in fact they are the first man and (alien) woman to wield a Infinity Stone together.
Hank Pym and Janet Van Dyne from Ant-Man much like the comics play this straight, as seen in a Flash Back where they work for S.H.I.E.L.D together as a married couple. Scott and Hope follow in their footsteps in Ant-Man and the Wasp and in Endgame.
T'Challa and Nakia in Black Panther, even at the start of the movie they reunite by way of taking out traffickers together.
Close -but platonic- example with Hawkeye and Black Widow in Budapest and the battle of New York, also Captain America and Black Widow invoke this in Captain America: The Winter Soldier.
The Matrix: Neo and Trinity are a downplayed example. While they work and fight together, Neo is The Chosen One and so Trinity can't keep up.
Starship Troopers: Johnny Rico and Dizzy Flores, soldiers of the same unit, share some love before going out to shoot up giant alien bugs.
The vampire Sonya and lycan Lucian in Underworld: Rise of the Lycans. Their doomed romance started the war between the vampires and the Lycans. They do quite a bit of swordfighting and monster-slaying, right up until things go south.
Selene and Michael in Underworld: Evolution. Besides their supernatural abilities, Selene is a centuries-old warrior while Michael combines the powers of both races.
Harry and Helen Tasker, at the end of True Lies. She's shown to have joined him as a spy, with them threatening a man together.
In Kung Fu Hustle, there is the battle couple of the Landlord and Landlady. Both appear as innocuous, though important characters that later in the film demonstrate incredible martial arts skill.
Katniss and Peeta work together in The Hunger Games except he doesn't know she's only pretending to love him in order to gain sympathy from sponsors.
In The Hunger Games: Catching Fire they are engaged when they go back into the arena. Their actual relationship status is a bit more complicated, as the engagement came about to placate President Snow, but Katniss is actually falling in love with Peeta. By The Hunger Games: Mockingjay Part 2 they fight in the same squad during the rebellion, and end up married.
Calamity Jane: Considering how Calamity Jane and Bill Hickok are skilled gunslingers and like trouble, you'd think they'd turn out to be this couple in an instant, but it's implied to be averted after they get together as both of them want to settle down and raise children. They've been close friends for quite some time, so it's not outlandish to assume that they played this straight at some point.
Bill's Friend: I don't know what kinda life you're gonna have living with that catamount, Bill, but it ain't gonna be dull! Bill: That's fer dang sure.
Spock and Uhura in Star Trek Into Darkness as they accompany Kirk to a war-torn world in order to track down John Harrison.
One of the possible configurations to operate a Jaeger in Pacific Rim. The Russian pilots of Cherno Alpha, Aleksis and Sasha Kaidonovsky, are married. And so were the Japanese pilots of Tacit Ronin, Duc Jessop and Kaori Koyamada.
In the soft - core porno Passion and Romance: Ocean of Dreams, Greg and Melinda Arnold met while they were serving in Vietnam. He was a Marine Corps helicopter pilot and she was a Navy nurse.
Navy surgeon LT. Don Jardian and Navy nurse LTJG Deborah Solomon in Purple Hearts become this while serving in Vietnam.
The Mutos from Godzilla (2014), in a sense, as they are a mated pair and manage to put up a real fight against Godzilla. One-on-one, they are severely outmatched, although the male one had the advantage of being able to fly.
Undercover Blues Jeff and Jane Blue, (not so)-ex CIA, currently on maternity leave for the birth of their daughter, vacationing in New Orleans when they are called back to retrieve some stolen MacGuffin. She complains when he brought their less than one year old daughter to a knife fight, and she has to interrupt the (humorous) interrogation of a bad guy to go to their crying daughter in the next room.
Assassin's Creed (2016): It is implied that Maria and Aguilar are lovers in addition to being fellow members of the Assassin Brotherhood.