Question: I decided that one of my characters is unable to have children. To keep it simple here, magic is behind the reason why she can not. I've worried a lot about how to explain her situation in the story because I want my readers to be able to accept the reasons I give them. In a story situation like this one, what is the best way to explain problems of a more personal nature without being blunt? Or must everything simply be "implied"?Answer:
It sound as though you are creating a mystery. Readers enjoy mysteries, but they also like to have the mysteries resolved or explained by the end of the story. In other words, you can imply things (provide clues) throughout, but if the magic that is preventing conception is a crucial part of the story, you may need to reveal what's going on at some point. This is especially true if readers need to understand the reasons why the story unfolds as it does. Don't worry about the "personal" nature of the problem. Readers expect to learn the personal details of the characters' lives. That's part of the fun.
On the other hand, the facts in this cased may not be crucial. Sometimes, a writer may understand details about the backstory which the reader never needs to know but which help the writer maintain a logical, internal consistency to the characters.
I can't give you a definitive answer because I don't know your story. I suggest you show your finished draft to a few people you trust. If several people tell you that they didn't understand or were confused about why this woman had no children, you may need to incorporate a better explanation into the story at some point.