You mentioned that this little spat is over the décor in the second living space. What's in the first living space? Who is dictating how that whole room is being setup? Colors, furniture, window treatments etc etc.
To negotiate from a position of strength start "demanding" how things will look in the first living space. Choose wisely and garishly as possible.
Then when she sees you're serious and finds how hurtful "demands" can
be the negotiating begins. One last thing, in this process do not raise your voice no matter how heated it may become. You'll see why as this unfolds.
Regards,
barts
To negotiate from a position of strength start "demanding" how things will look in the first living space. Choose wisely and garishly as possible.
Then when she sees you're serious and finds how hurtful "demands" can
be the negotiating begins. One last thing, in this process do not raise your voice no matter how heated it may become. You'll see why as this unfolds.
Regards,
barts