Or she could've taken up smoking on the sly? Paranoid much?

Second Hand Smoke Breath?

it doesn't have to be your roommate.

abahahahahhahaa #6 good plan. U should so do it. She prob is a cheating hoe

im with #6. #9 is a little outrageous.

I like #9's suggestion. Hey, maybe she isn't cheating on you with your roommate. Maybe its some other random guy that smokes. Maybe a guy she met late one night in a bar. Maybe its a homeless guy who got a bit more than change. Maybe its a sixty year old addict. Or maybe its all those guys AND your roommate. Don't be so quick to jump to conclusions. Regardless, lose her ass.

smack the bitch. right across her dirty mouth.

Did you even bother asking her?

maybe she just had a smoke .. u should actually talk to her .. and ask her instead of jumping to conclusions..

Unless the guy was smoking at the time they made out, actively blew smoke into her mouth, and she ran to kiss you right after, I'm not sure how this could have happened. She probably smoked one herself, maybe your roomate let her smoke one because she wanted to try, please just ask her before possibly making a big mistake.