What do I do??

I love my boyfriend to death and I would do anything in the world for him but he has this flaw, hes not one to show PDA in front of his friends or in front of anybody.....but when we're alone hes all over me i like to show other poeple that im in love but I geuss he doesnt. (when I say PTA I dont mean just kisses and huggs) Is there anyway that I can get him to show some love??