Hi,
It does sound as if your girlfriend’s cannabis use is an addiction and it’s sad that she didn’t continue with the NA meetings.
If you would like some support for yourself please contact us at The Icarus Trust. We are a charity that provides support to people dealing with a partner or family member’s addictive behaviours. We offer a free service and you might find it helpful to talk with one of our trained and experienced people.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
All the best.