its just that most people don't party like that in their 30's, so like you suspect she's just catching up with that lifestyle. This is very common with ex muslims, particularly women since they have been actively shielded from it. Hopefully she's aware of the dangers. I don't think that you should be worried because she'll most likely relax with excessive partying. Im not an atheist but an ex-muslim.
She's not an ex Muslim, she still says inshallah and other religious invocations. I will try and be there for her. I'll pray she's guided.
What do you believe in if you're not an atheist?