My partners mom is a Narcissist

Hi folks, this is my first (SECOND!! this is a repost teehee) Reddit post so I’m new to this and I suck at writing so sorry
So as the title says, my (M21) partner (NB21) has a narcissistic mother and I’m just extremely confused on how to navigate everything. Their mother hates me because I’m not ‘good enough’ (not rich) and my family is horrible for ‘how they act’ (We were having a celebration party and people were drinking and smoking). She also couldn’t care less about any of my partner’s choices or opinions. It always backfires into somehow making it about her. And it seems like she’d rather let them suffer alone than live their life.

I expect on one hand for people to have a distaste for drinking and smoking if they don’t partake, whatever. But she seems very intent on the fact I want to lead my partner down that path. I don’t but I figure once she’s set in her ways she’s stuck.

I couldn’t care less about her opinion but it’s destroying my partner and their mom doesn’t even let them out without 21 questions and if it’s me it’s absolutely not. She wants us to break things off but we absolutely both don’t want that.
Any advice? Please lol

TLDR: Partners mom doesn’t like me and paints me as the not good enough poor guy who’ll ruin their life and their mom gives them no freedom. Any advice?