Thie reminds me of that "Nana's Revolution" manga. It was pretty much like this, the mc's best friend would do manipulative, nasty things to make mc miserable so she can have her all to herself.
I take back what i said, the ending suck. All of the lovey dovey is just a bait, no more no less. The fucking ending just ruin the whole story for me :((
spoil that please
but thanks anyways, now I don't have to be sad about never getting to read the rest of it