She is his would be/ wife to be

In India there is a tendency to call a woman or a man as would be in the sense of his future wife or her future husband.

She is his would be ( wife)

He is her would be ( husband)

I have found the expression wife to be.

Is there an expression husband to be?

Is _ Would be _ or would be wife idiomatic in native English speaking countries?

Solution 1:

Summarizing/extending the comments:

Fiancé is used to refer to someone who is formally engaged to be married, but the marriage has not yet happened. Sometimes people add an "e" to the end (i.e., fiancée) to refer to a female, but not reliably and "fiancé" is often used as a gender-neutral form. Grammatically, you almost always hear it in a possessive context, as in "that is her fiancé" or "she is my fiancé".

If the two people have yet not agreed to marry or the marriage is not otherwise arranged, then the concept is expressed exactly the way you did when you asked the question, i.e., "future husband" or "future wife". Note that this connotes that the marriage is speculative and may not happen, though it also connotes that at least one person wants it to happen.

Example pop culture quote from Big Bang Theory: https://www.quotes.net/mquote/886545

"Would-be wife" is a little different. "Would-be" in that context means "has the potential to occur" (https://www.merriam-webster.com/dictionary/would-be). To me, it connotes that the marriage might happen in different circumstances, but something would have to change before it does.

Solution 2:

In the US, I've seen the term would be X referring to something that would have, under given circumstances, been something, but for some reason, it didn't come to be this way. For example, a would be doctor might refer to someone who was studying and was ready to receive their doctorate, but then suffered an accident that caused this person to miss their final exam, thus (in this case, temporarily) denying them this status.

In that sense, I don't believe that in the case of certain future marriage, you can use this idiomatically to mean husband/wife to be. But as far as your second question, the term X to be can be applied to anything that will become that thing.

Here's a short, quick list of examples using X to be:

Graduate to be
Someone who will soon graduate from a university

Husband to be
A man who will soon be married

Lawyer to be
Someone who, presumably, will become a lawyer in the near future

...and so on.

Keep in mind that here, using X to be, you are referring to a title, status, or other such stature. Adjectives don't work there. It is unnatural to say happy to be, for example, with this meaning.