Hey there!
Right now I'm lookinf for an manga but I already forgot its name.
Ehm, it's about a student boy who falls in love with a work mate and as they're going out it turns out that she's a BL-Otaku. She wants her boyfriend to write a fanfiction about something and yeah.
There also was something with Sebastian-Uke or something like that xD

Hope it was understandable xD

Fujoshi Kanojo - havent read much (only first chapter) so cant tell about the "writing fanfiction" but the first part kinda fits.