Correct error in perfect tense

Question

I'm self-studying English and in an exercise I'm asked to correct the errors in perfect tense of a series of sentences. One of them is the following

Supposing they would have got married, wouldn't the day have come when they got bored with each other?

The solution is:

Supposing they had got married, wouldn't the day have come when they got bored with each other?

I have two questions about this.

1. Does "they had gotten married" work in the first part? Assume I'm trying to fix it by using American English.
2. I'm confused by the second part, specifically "got bored". I feel like "when they would have gotten bored" segues much more naturally from "wouldn't the day have come" than "when they got bored". Do both versions work? Do they say the same thing?

I don't really know grammar. I speak correctly for the most part, but I don't know the rules of grammar explicitly, nor the technical terminology, so please try to adjust your answers as much as possible.

Answer 1

What the answer is drawing on is possibly the notion of ordered conditionals 1, 2. The two of them never got married. The notion of their marriage is a hypothetical. This leads you to a so-called type 3 conditional and to the past perfect in the first part of the sentence (the conditional clause).

Had they got/gotten married ...

If they had got/gotten married ...

Your question around the second part has an answer in style (and not grammar). The author wants this dramatic formulation of "the day will come when X will happen", instead of the plainer "X will happen".

So, instead of:

Supposing they had got married, wouldn't they have eventually got bored with each other?

We end up with the wordier version:

Supposing they had got married, wouldn't the day have come when they got bored with each other?

Answer 2

Here, we have to work mainly on two clauses:

1. Dependent clause - Supposing they would have got married (It is dependent, because it cannot stand as it is, alone)

2. Independent clause - Wouldn't the day have come... ? (This can stand alone; hence independent). Now, see the following examples.

Some more examples: If they get married, the day will have come.... If they got married, the day would have come... If they had got married, the day would have come....

In the sentence "Supposing they would have got married, wouldn't the day have come when they got bored with each other?" The second clause evolved this way:

The day would have come Neg. They day wouldn't have come Neg.Que. Wouldn't the day have come....?

As the solution tells, the tense in the starting clause should be Past Perfect. Now, can you related the question with the corrected answer? Supposing they had got married, wouldn't the day have come [when] they got bored with each other.

Supposing you had not asked this question, I wouldn't have answered this way. Means, If you hadn't asked.... I wouldn't have answered.....