Interesting. The well is dry to me means "the relationship has burned out".

"The well is dry" is a known expression to mean a valuable resource has run out. It doesn't have to refer to money. It could also refer to a lack of inspiration or motivation. "I went looking for inspiration, but the well was dry"

There's also derived idioms such as the Natalia Imbruglia song "Torn"

" There's nothin' where he used to lie Our conversation has run dry "

There's no mention of a well there, but "has run dry" comes from that expression.

It's not often used in spoken speech though. It would definitely sound weird if a non native speaker used it in conversation.

It means a supply or resource has been exhausted. If in this drama, a person was asking for money, then yes, it means there is no money. You can also use it like this... "She cannot write any more books; the well's run dry" to mean that she has exhausted her ideas or creativity to write more stories. I hope this helps!

This is totally new for me as well!!! I've never had heard this Expression!! 😬

The brother may or may not have more money (probably still has a fair amount). Usually it means someone has asked the same person too many times for money or favors and the one giving those is no longer willing to help.

That is a colloqial phrase that is sometimes heard. I don't think that I've ever used it.