I've a little problem with location of couple poses.

This might be the issue you had with the pose ceasing to function. When moving the entire model in Blender you should only use g when you're in object mode or when you're in pose mode with the b_ROOT_bind_ selected. In game they came out pretty close to what I wanted although, as I said, I think I was working with them too far away from where the pose would actually start in the game so I got some clipping. I saved the x one directly and used save as for the y model. I then went into pose mode and made the pose for the x model and then the y model. I moved each Sim away from the center point by grabbing them in Object Mode and rotated them to face one another. Then I appended the rig and model parts of y into the same. I exported both as create new and opened the x one in Blender. One used the buzzer success interaction x and the other used the buzzer success interaction y. I used the mischief buzzer trick to trigger the pose and this is what I ended up with: So I'm thinking Sims 4 might use about 0.35 as a start point too.

In Sims 3 the couples animations started out with each Sim 0.35 back from the center point (the point where the pose model shows up in Blender.) For my test I started with each 0.5 off from the center point and in the game that made the Sims too close indicating that 0.5 is further away than they will actually start their interaction.

I haven't done a whole lot yet with couples poses but I just tossed a test one into the game to see what's going on with them.

Sims 3 couch couple poses