I'm just really curious, who does everyone think died? I know I probably shouldn't think that into it, but I can't help and be curious about it. Like I said before when the first episode came out, I don't think any of the main cast died. Or even any they are together with. I do think it is someone close to all of them, but I'm not too sure who it is, and even if we were introduced to the character that passed away.
I have a random theory that it was a pet or animal they all took care of at some point in the series that they all grew close with. But that's just a stretch.
Also, I also wanted to add on: I think it is interesting that the first season ended with marriage and the 2nd season is ending with death. I like how that part about how they started it and will end it.