Do couples act differently in social situations?

me (25) and my bf (29) have been together for a year... everything is fun %26amp; great but whenever we are in a social situation we both get very quite, my bf also becomes rude %26amp; arrogant... we don't even talk with each other much, which is so the opposite of what we have when we r alone... is it something weird? am i suppose to take this seriously? why is it like this?Do couples act differently in social situations?
Well think about it, you are with him all the time. When you guys finally get out in a social group you'll bound to interact with other people besides yourselves. Otherwise whats the fun of going out in a group, if you just wanted to sit in your little circle and be alone then you would be out alone or at home!