I (16M) have a best friend Marcos(16M) all fake names. I have been friends with this dude for over 5 years now. I have told him almost all my deep secrets and I can tell him with anything. I can surely tell he is the only person I can trust.

Marcos has been dating a Clara(15F) from our friend group for over a year. We all smoke except from Marcos and Clara. Marcos has said verbably that he would break up with her if she smoked.

Today, 6 people from our friend group had a hangover at Marías's(15F) house. From the moment we got in we started to vape. Clara was hesitant at first but the se tried if just to learn the flavour. Then she started smoking with no regrets and even learning some tricks to do with the smoke.

I love all my friends and I do not want to create tension bettwen the group or anything and surely I do not want Marcos to break up with Clara. This is the only real friend group I have ever had and I don't want to lose it. So, would I be the AH if I told my best friend that her girlfriend is smoking?

To any of those that want to scold me or my friends for smoking, I don't care, I do it only on holidays (like Semana Santa, a current holyday in Spain) and it doesn't affect me academicly.