There's this manhwa (or maybe manhua? I’m not sure how to spell it) where the MC is a swimming instructor. He teaches both women and men how to swim, but there's another instructor who's a total professional. Naturally, all the baddies flock to him, leaving the MC stuck training either men or, uh… women who aren’t exactly his type (no offense — every woman is beautiful in her own way, and I fully respect that)
Anyway, the MC basically wants to teach the fine ones so he can eventually hook up with them. Near the end of the story, he ends up getting involved with a rich woman a total MILF. They hook up toward the conclusion of the story.