Mr. and Mrs. Smith (2005)

This romantic comedy action film directed by Doug Liman with the main Casts Brad Pitt and Angelina Jolie.
The story begin when they met five or six years ago in Bogota, Colombia. There bored marriage was really bored and that they cannot remember themselves when was the last they had sex.
They learn that they are both assassins hired from different agencies. They are assigned to kill Benjamin "The Tank" Danz, they cross their path and hit each other. They don't know yet that it was Jane, his wife and on the other hand, Jane doesn't know that it was her husband who hit her.
After the war in their house, they both realized that they still love each other. They both cooperating to get their target.