A relationship rests on how much you talk, how well you talk and what you talk about. It would be difficult to define the just right and simply wrong when it comes to the first two, but of course, there has to be a deliberate effort for the third! If you want to evade the sher-ke-mooh-mein-haath-daalna situation, don't talk about these things to your girlfriend!
Why would you even do that to yourself?
This is a grey area you don't want to visit. Say hello to shopping bills in case your salary is too high and goodbye to a girlfriend, in case it is too low.