I think my girlfriend smokes?

[SilentHowl]

*Facepalm at the posts above*

Ask her, simple as that. Tell her you've been hinting at it from facebook and what-not, and that your concerned. Of course your not over-reacting, you're just being a good boyfriend. It can do harsh damage to one's body like trigger or cause brain disorders, harm her lungs, etc. It's best just to ask her about it, why she's doing it and how you can help stop. If she keeps denying it then you can't be with someone who won't be truthful to you.