Well, yeah...you went for looks when you chose her. In which case, you need to admit something to yourself...the physical is the most important part of the relationship for you. She knows it. Just lay off the touching in public, because it just shows how insecure you are with her looks...touching her when she doesn't want to have that happen in public is just saying "She's mine! She's really mine!"
Strategy on this. When you get physical with her, give her the shagging of a lifetime, but be a bit blase in public...because, she know's who doing her right and if you know that she knows, you won't be so insecure about what is really nothing more than very good sex.
If all it is physical, then it is soo fun to go out with her public because the hormones (hers and yours) just ooze the fact that you get her off and she's addicted to the magician
Of course, if it isn't just physical...well, who are we kidding...of course that is all that it is in this case! Duh!