Originally Posted by The Succubus
So don't use words - let your girlfriend see you smile when she makes you happy and when she makes you feel warm and fuzzy inside, give her a hug. You can say a lot more that way than with a word.
This is actually quite a good idea. Tilt your head slightly and smile at her, nay, beam at her, in that special way until she looks at you and says "What?" - then reply with "Oh, nothing. Just... you."