Incorrect grammar vs dialect (when/whenever)

My good friend is from Pittsburgh and frequently uses the word whenever to mean the word when. I am aware this is a regional dialect and really wish to respect that, but it is causing numerous problems in our spoken communication. (I am also a native English speaker but am not accustomed to this usage of "when" and "whenever".) I have expressed my concerns to him and asked him to use a neutral dialect to improve communication, but he argues it is valid English, he doesn't understand the difference between the two anyway, he "doesn't have problems with anyone else understanding [him]", and that my misunderstandings are because I "have Asperger's and understand [his] speech literally". (I would guess if no one else has an issue with his speech, it's because he speaks English primarily with people who have the same regional dialect and non-native English-speakers and uses French and German for work. That said, perhaps everyone else does understand what he means without any confusion. When I ask for clarification, he gets irritated.) What should I do?

Examples of such misunderstandings are below:

Example: Whenever my aunt was about to die, she called me into the room and told me she loved me.

I understood this as his aunt periodically became ill to the point where she was close to dying and called him into the room to say she loved him. (My background in healthcare makes this seem like a very plausible situation.) I responded to him in a way that reflected my understanding of the habitual nature of this.

He was annoyed and said it was obvious that the aunt was about to die one time and that, as such, this calling-into-the-room was a one-time occurrence.

Example: Whenever my sister was born, my dad fainted.

It is obvious to me that his sister was born one time. In this instance, although I believe the better word choice is when, I can understand that his father fainted when his sister was born.

Example: Whenever I moved to Germany, I lived in Berlin.

I knew he had moved to Germany once for a (temporary, location-based) job. However, his statement surprised me, and I thought maybe I was wrong (and as a friend I wanted to learn more if he had actually moved numerous times), so I asked how many times he'd moved to/lived in Germany. He was equally surprised by my question, responded he'd moved to Germany once, and could not understand how there could be any confusion in the statement.

As Wikipedia says, "all scholarly research in linguistics is descriptive."

What you reported are good examples of the "punctual whenever", which is a grammatical feature of Western Pennsylvania English that differs from General American. Wikipedia cites Montgomery, M. B. (2001). "My mother, whenever she died, she had pneumonia": The history and functions of whenever. Journal of English Linguistics 29(3): 234-249. and provides these details:

the "punctual" whenever sub. conj. "at the time that" (Montgomery 2001).

• Example: "My mother, whenever she passed away, she had pneumonia."
• Further explanation: punctual descriptor refers to the use of the word for "a onetime momentary event rather than in its two common uses for a recurrent event or a conditional one" (see above citation).
• Geographic distribution: In the Midlands and the South (see above citation).
• Origins: Scots-Irish (see above citation).

The examples would be incorrect grammar in General American, but it seems your friend isn't trying to speak General American---he indicated that he's happy with the way he already speaks, and doesn't want to explore it further with you.

What should you do?

• Option 1: Continue asking your friend for clarification when he's not in the mood. (not recommended)

• Option 2: Accept that your friend uses "whenever" in this way, and remember how this works in his dialect whenever you hear him use "whenever" and want to know what he means.

• Option 3 (my recommendation): In addition to option 2, become an amateur (or professional) linguist by reading articles about Western Pennsylvania English, so you can relish in recognizing many more grammar quirks your friend may use which you may not have noticed before. Post questions about them here or on linguistics.SE if you're so inclined.

I read this out loud to my wife, and she said she understood perfectly what your friend meant, which surprised me. After some discussion, we agreed that what your friend is intending to say is, "Whenever it was that my aunt was about to die, she called me into the room and told me she loved me." And, "Whenever it was that my sister was born, my dad fainted." And, "Whenever it was that I moved to Germany, I lived in Berlin."

For him, "whenever" seems to have become a spoken shorthand for "whenever it was," meaning he doesn't necessarily recall the exact date and time, but rather what was important to him about the event. If you can accept this understanding of his speech pattern, then your problem is solved: it's just the way your friend habitually refers to an event in the past.

I grew up in the suburbs of Los Angeles in the 50s and 60s, when teenagers habitually peppered every other sentence with "like" and "you know" and "for sure." Example: "Like, we went to the mall, you know, and she was like, 'let's get some new jeans,' you know? And I was like, 'for sure,' you know?" My English professor, who rode the bus to work, would sit behind a couple of teenagers and jot down a hash mark in her notepad for every time one of them said "like," "you know," or "for sure." It was very amusing and so widespread that a name for them was created in popular culture: they became known as "Valley Girls," short for girls who were raised in the predominately white, middle-class San Fernando Valley of the 1960s.

So yes, it is incorrect usage, but so what? I'm sure your friendship is much more important to you than his quirky misuse of a single word. :-)