Now, first off, it was almost perfect for most of the runtime. I watched the compiled version of the first four episodes, and by my calculation, it was almost perfect until what would be the last episode in part 1.

They set up the connection between the leads very quickly and very well, and the conflicts they introduced were new and played very nicely into the set up. Even until the ‘last’ episode, the story building was incredible, I'm just angry with the way they handled one aspect of the conflict.

For a short series, they managed to stuff in conflicts about work, economic disparity, sexual experiences and unwarranted jealousy, but of course the one that caused the most damage was the oldest page in the book, the love rival.
The character is of course completely unreasonable and coming off borderline stalker - ish, but they're just doing it because they like one of the leads! Ugh-
In a matter of a few minutes, they managed to overshadow the good chemistry and connection the leads built over the past few episodes. All that hard fought connection, down the drain.

Finally coming to the second point, I'm not going to reduce my rating since I know there's a part 2, but I get how frustrating it must have been to watch a series end like THAT. Come on, you don't do that.