[Sunny heroine at first, melancholic later x good guy unmasked as a bad guy]
Hu Taoye had a boyfriend. Then she didn't. Soon after, a really great guy came along, and he became her boyfriend. But this nice guy was kind of exhausting. He was always getting upset, and she was at her wit's end.
Gu Xingzhi's rise to the top: get rid of the boyfriend, take his place, and take over everything in his girlfriend's life: her friends, her job, her family...
Get rid of her friends, take up her time.
Get rid of her job, take up her time.
Get rid of her family, take up her time.
Get rid of...
By the time he'd gotten rid of everything, Hu Taoye finally noticed. Things started spiraling out of control.
Note: A product of giving up and going with the flow. Read with caution.