I read the Bunny Drop manga (yeah) very long ago, butI don't remember it addressing that aspect of Rin in any meaningful way, with the exception of the last 3-5 chapters were suddenly she wants to fuck Daikichi. Tbh the whole second half of the manga is like a generic shoujo with a ~twist~ ending more than anything else.
I getting impression the author actually always wanted to write that kind of story and the parenting part just a big buildup.. but the audience clearly doesn't like it (for obvious reason lol) and cut short.