Help! Room divider affects structure of physical walls.

[dallin]

On this second floor plan there is an angled step down into the living room. I created the walls and then connected them via a room divider, selected the room and set the floor height to -24" to create the step down. Everything worked how I hoped except, once the room floor height was set the ends of the existing physical walls angled (to connect to the room divider wall as if it were also a physical wall). I do not want the ends to angle. I want right angle, squared off ends. Please help, thank you 

[dallin]

Apologies this is my first time on the forum, thank you for letting me know, I am using latest student version. 
 

Yes the red marks you have made is how I’d like mine to look

[dallin]

i did this