Anna-san no Omame

Lilly is a young woman who always seems to misunderstand things (in her advantage). Therefore she always misinterpretes the behavior of those people around her.

For example: She believes that she is the most gorgeous woman around and on account of this every man wants her.

She also believes that Anna's boyfriend is in love with her. Anna is Lilly's best friend who is sharing an apartment with her...

source: https://www.mangaupdates.com/series/0f48vxa/anna-san-no-omame