Depends on the age.
If your 20+ take charge in the bed room to show her you've got the "upper hand". Us females really like men who can provide and protect. Even if you dont care that other guys look at her, next time it happens (or maybe fib a little) lean into her and whisper in her ear that you really dont like the way that guy looked at her...or when your sitting on the couch scoop her up and take her to the bed room without asking and tell her your glad she's all yours...
Take control of minor situations, it will give her the sense of...stability...in you
:) good luck!
-Anonymous