Help finding a story I once read

[Drakory]

Hey I would appreciate any help in finding a story I read a few years ago but have been unable to find since.

It's about a Male Student/Female Teacher(Might have been a nun, I forget)
The teacher pretends to be a teenage girl in public so people don't know it's a teacher-student relationship during school
He proposes
Might have been a series, or a very long 1 part story
During a part of the story a girl starts to like the guy and suspects he's dating the teacher

Any help finding it would be appreciated.

Thanks,

Drakory