“What if your girlfriend insists that you wear certain styles of clothing because you are ‘showing her up’? Why does my girlfriend insist that I’m always turned out and color coordinated? If people are going to look down on me because I don’t always wear smart outfits then they are not the sorts of people I wish to impress. My girlfriend says that she loves me no matter what but still gets concerned about how I’ll make her look in front of others. How can I broach this tactfully?”Tact is not going to do it. You are going to have to loudly declare that your girlfriend is relieved of all further responsibilities regarding your attire. If you allow her to dress you (so she will look good) the day will come when she will decide what you will and will not say (so she will look clever!). Then she will decide with whom may or may not talk (so she will not feel left out).
If she loves you “no matter what” she’ll respect that you are a separate being. While she thinks your clothes are a reflection on her she is apparently devoid of the healthy boundaries necessary to sustain a healthy long-term relationship.