An electrical connector assembly includes a first connector and a second connector mateable with each other wherein each of the first connector and the second connector has an insulative housing essentially composed of a bottom wall, a side wall and a pair of end walls wherein all the bottom wall and the side wall are rectangular while the end walls are right triangular. The first connector and he second connector are coupled with each other in a complementary manner with the corresponding hypotenuses of the right triangles confronting each other. A sealing member of a frame structure is located at an interface between the coupled edges of the housings in an oblique manner.