Girls sometimes are like small kids. They need not only our full attention, but some affirmations as well. Once in a while my girlfriend would ask me whether she is pretty.
I know guys, that you all are wonderful out there, and on several occasions you have already told your girlfriend, that she looks gorgerous, or even absolutely amazing, or just really pretty. However, if you caught yourself in the same situation again, you can always answer: you are always gorgerous.