La Pluie's lack of a well-thought-out story, even with its vague hearing loss gimmick, is its undoing. An underdeveloped script is exposed the longer it goes.

A unique premise needs high level understanding of screenwriting to pull off successfully, especially in a series. Otherwise, the unique premise can prove too much for the novice to handle.

The result of a poor script don't just apply to the audience. The cast can be left to flounder with unclear or nonsensical character motivations.

La Pluie's faults are not rare in the BL space, but viewers are desperate to see them improved. To improve the BL space is to ditch the entire premise.

Your goal should not be to write/produce a "BL", your goal should be to create a great story for screen that just so happens to have a same-sex couple at its core. This would broaden project appeal to a wider audience, attract better talent and generate more revenue.

As for La Pluie itself: I would have challenged myself to write a first draft outline of La Pluie without the hearing loss premise. If we can craft a good story without the premise, then the foundation is laid as you then go about adding in said premise in future drafts. The ending should leave open the possibility of a second season, while also providing some closure.