Why wasn't

Why wasn't
 

-And I should think you'd consider me sometimes. If we had a fourth wall, why it'd be just like this room wasn't ours at all, but all kinds of exotic people's rooms.

What do the red words mean? The subject of WASN'T is WHY, but OURS becomes inexplicable; this OURS seems to be different from 'His plan is better than OURS'. What does it refer to in the sentence? Additionally, 'but all kinds of exotic people's rooms' makes no sense within this sentence structure. Could you help me out?

The subject of "wasn't" is "room." And the verb could have been written "weren't" (subjunctive mood), but it is colloquial the way it's written.

The word 'why' is an interjection, not a subject. In fact, the word 'why' can never act as a subject unless it appears in the plural.

I'll rephrase the sentence to see if it helps any. I've left out the interjection and used the subjunctive mood where appropriate. Where 'that' appears, it refers back to the room.

If we had a fourth wall, it would be as if the room weren't ours at all, but that of all kinds of exotic people.

And I should think you'dyou would consider me sometimes. If we had a fourth wall, why it'dit would be just like this room wasn'twas not ours at all, but all kinds of exotic people's rooms.

Now, is it easier to understand?

I think it should be kept as WASN´T/WAS NOT and not WERE NOT/WEREN´T.

Whenever you see apostrophe + D (´d), it can be should/could/would... as the expression, Shoulda Coulda Woulda but didn't. (regretting the past)

All kind of exotic people's rooms.
Rooms of exotic, different people
The room that belongs to people that are exotic and different
The exotic people who are very different, have a room

The room is NOT exotic nor different, it's the people... this can be the confusing part.

Off topic:
Should've Could've Would've (Should+have)
From this example, this is why people make the mistake of Should+Of instead of Should+Have, etc.

Thank you Rusty.

For another replier, are you a native US English speaker?

Replier is a correct term, just weird but Google said responder and answerer are correct synonyms but with internet forums, I'd (I would) say poster but this is not so important.

Yes, well, Korean was my first language but I stopped learning that when I was 4. This sentence is indeed weird but if you were to take part of the sentence and change it into present tense, it would be easier to see and sounds more fluid.

I asked my brother in law and he said he thinks weren't then he gave me the example, "If I were you." Then I broke up the sentence and re-arranged it as shown below.

If we had a fourth wall, why it'd be just like this room aren't ours at all
If we had a fourth wall, why it'd be just like this room are not ours at all

Neither of the two sentences sound correct. My parents have a store in the ghetto and I always hear, "Yes you is" which everything looks like the words are in agreement because they are all singular thus in agreement but if you are a native English speaker, you know it is "Yes, you are" as it sounds correct. Notice how I said looks and sounds, that is because it doesn't necessarily follow a strict rule.

So below, it sounds correct to me but we can play with it a bit more.

If we had a fourth wall, why it'd be just like this room isn't ours at all
If we had a fourth wall, why it'd be just like this room is not ours at all

The room are black
The room were black

The room is black
The room was black

Those are ours - (Those = plural)
That is ours - (That = singular)

Our/s is not used to determine singular or plural.

The reason I chose 'were' is because it is the subjunctive form of 'be' and the subjunctive, although it is falling out of use in American English, is what mood that part of the sentence takes. We aren't dealing with real events.

The simplest way to write that last part is, "It would be as if this room weren't ours at all." (In colloquial American English, "wasn't" may be heard more often than the subjunctive form, but a speaker of British English would use "weren't," and the OP is learning British English.)

Ahh, that makes sense why we say, "If I were you". That is quite interesting, I don't think I've actually learned that rule in grade school. Yes, British English can be very different. In my Spanish class, my British classmate said she was queuing (to queue) in line the other day. Americans don't use that word as a verb, we say to wait in line but sometimes with intangible places like the internet, wait in queue. Now to think of it, it's like how Americans say exercising as a verb but in Spanish we need to use hacer + ejercicio.