i only remeber two people in a cabin that is in the woods or like a mountain or something and they are to take suicide but one of them has tricked the other by not loading his/her own gun, there is also some type of cop or detective involved that goes to the cabin last second and the person who tried to trick the other person dies by like falling of from the cabin/house
It’s Murder by Numbers (2002)
Sandra Bullock plays a detective investigating 2 teens who commit a murder. Finale includes the murder/suicide scenario in a house falling off a cliff.
Sounds like Fallen, with Denzel Washington in it. That movie was crazy scary!