I can't remember the name. What I remember is that the female lead had some kind of serene magnetism that captivates every single man and there's this art teacher that's been using her as his muse (and mistress) for several years. The story is told from the POV of some college-aged art student, and there's some middle school girl with a bob-cut thrown into the mix too. The female lead is incredibly devoted to the married artist guy, even though every male in the series is inherently in love with her. It also takes place near the ocean.

Sounds like Omo ni Naitemasu

Yeah, that's it. Thanks!