On filling out forms for consent order/finances, there is a question about
cohabitation and whether you
are currently or plan to do so in the near future.
This question
if answered yes could result in the judge believing that your housing needs
are met and that you will be spending less than someone living alone
(either raising children or not). This could easily go against you in the
allocation of the finances. You would not NEED to spend so much money per
month as you are sharing bills. Your ex on the other hand would be
spending more on rent/bills because she is alone, the extra from your pay
packet may be what was needed by her to balance the situation.
You not moving in with your girlfriend has nothing to do with your ex
wife controlling your life and more to do with you controlling the amount
of money that leaves your pockets.
Hope this helps
K/x