Molecular dynamics simulations are used to determine how the presence of a water surface affects the way that bent-core surfactant molecules interact with one another. The simulations are carried out for isolated pairs of bent-core molecules, and for pairs of bent-core molecules on a water surface. The results show that the water surface fundamentally alters the nature of the interaction between the bent-core molecules: a stable complex is formed when the two molecules are on the water surface, but not for an isolated pair of molecules. This difference occurs because the water surface constrains the internal structure and orientation of the molecules, which makes the packing of the molecules into a stable complex more thermodynamically favorable.