People there always talk...,

[Silverobama]

I haven’t seen Yan for a while. He’s a friend who I met in a coffee shop a few years ago. I asked him if he still went to the coffee shop (because there are many English club meetings) and he said from time to time. He said “Well, Silver, I never ask you this, why don’t you go there any more?” I said “People there always talk about politics-related stuff and I’m really not into it, so I quit”.

Is my italic sentence natural?

 

[tedmc]

I said “People there always talk about politics-relatedc stuff and I’m really not into it, so I quit”.

Is my italic sentence natural?

Yes, it's fine.

 

[tedmc]

What's wrong with the rest of my editing?

 

[emsr2d2]

I haven’t seen Yan for a while. He’s Yan's a friend who I met at an English club in a coffee shop a few years ago but I haven't seen him for a while. Recently, I asked contacted him to ask if he still went to the the club at that coffee shop (because there are many English club meetings) and he said "From time to time. He said “Well, Silver, I've never asked you this - why don’t you go there any more?” I said “People there always talk about politics -related stuff and I’m really not into it that, so I quit”.

See above. It's better to introduce Yan and how you know him first. If you haven't seen him for a while, you have to make it clear how you managed to ask him if he still goes to that coffee shop.

If you really want to keep "stuff" in your response, say "political stuff". I'd just stick with "politics".