I have learned over the past 3 years to not argue about stuff like that anymore. It's tiring for me, it strains my relationships, and frankly I'm more and more convinced that it undermines actual present organising. I read a couple of articles and listened to some podcasts on climate change and leninism (i.e. socialist revolution; professor Kai Heron) and their argument is convincing enough. We have bigger fish to fry than internally fighting over who was better 70 years ago. Like waaaay bigger fish: climate change and neo-fascism. Let's fry those first and then we can discuss Stalin and Trotsky and Chinese reforms and what have you.
An example from my hometowm. Almost every dedicated Marxist grouping here is Trotskyist. It refrains me from joining them but I also haven't asked them WHY they're Trotskyist. And also our dedicated communist party renounced its founder because they defended Stalin. Maybe it's the classic falsehood of "Stalin bad, Trotsky would have been better" or maybe they actually engage with Trotsky's ideas of permanent revolution and find them more helpful in the 21st century. I don't know. But this also means that I am left without a serious means of organising in my home city as I don't have time nor energy to start my own organisation and even so, the zeitgeist here is not one of pro-Stalin. So I don't argue it and just look at axtual actions on the ground and while Trotskyist, these are the people organising, fighting, getting out etc. So it's a dilemma.
I would say unless your GF is a fascist or right-winger, don't bother straining your relationship with this. Just inform yourself and that's good. (Unless you want to strain your relationship in which case, have at it.).
Nice, I do follow them but wasn't aware of this. Thanks comrade.