"What's Wrong?"

When a girl asks, “What’s wrong?” it’s because she honestly believes something is wrong, and will continue believing so until the air has cleared. If you want to convince her nothing is wrong, don’t say “nothing.” I know, we girls are odd like that—but seriously. A whole lot more has got to go into the convincing part for us to believe. Sorry, more work on your side; but that’s just the way things are. Obviously, something has given us the impression something is wrong, and "nothing" wont change the behavior that set us off in the first place.

Suggestions:
-Ask, "Why do you think that?" (in a calm, non-confrontational manner)

-Validate her concerns: “I can see how you thought that.” (woman—and men—need constant validation, especially from those they care about most)

-Explain how you are currently feeling in life, even if it clearly depicts how happy you are. (or helps you see where you may be giving wrong impressions)

-Apologize for making her concerned (yes, even if it wasn't intentional and you had no idea you were doing it)