I'm not going to tell my girlfriend I walk my dog with my best friend every night, can I trust you to keep that between me and you?
Oh for real now? Why wouldn't you tell her? Are you hiding something?
I am trying to avoid a fight.
You may think you are doing something nice, but it's not going to end well. You shouldn't hide things from your significant other.
It's not like it's something bad. That woman would just still get all over me for this.
I know how you mean, it is better than starting a fight. But maybe if you mentioned it to her with a deeper louder voice she will not be so overbearing. Sometimes people get a feel for your personality and try to run over it so to speak.