What is the underlying meaning of this sentence?

Question

I came across the sentence below. I am confused about the meaning the author tries to express, especially about the nuiance attached to the bolded pronoun 'that'. This list is the possibilities that I could think of.

1. All: All the prospective spouses are not good enough. Thus, so many look right past all of them.
2. Some: Some of the prospective spouses are good enough but some are not. And they look right past prospective spouses who are not good enough.

So many put off marriage and look right past great prospective spouses that simply are “not good enough.”

Answer 1

"That" is a relative pronoun, and it links the relative clause "are “not good enough.”" to the noun it modifies, "spouses".

The relative clause is clearly a restrictive relative clause, and so it means that some prospective spouses are not good enough. But looking at the context you note that these people haven't married yet. So we can understand that all the prospective spouses that they have met have been not good enough.

And just to add to the nuance, there is a layer of irony. The quote marks mean that the person thinks that they are "not good enough" but in truth they are actually great potential spouses.

So the conclusion is that the people who have postponed marriage believe that some of the prospective spouses, including all that they have met are not good enough but in fact, most or all of them are good enough.

Answer 2

Determiner that, in this context, means "those, which are.."

Correspondingly:

So many put off marriage and look right past great prospective spouses that simply are “not good enough.”

could be understood/translated as:

So many postpone marriage and look right past great prospective spouses, which simply are not good enough.

Answer 3

... great prospective spouses that are X means that the the speaker/writer is limiting the spouses he/she is talking about to only those that are X.

Of what you posted, this is the most correct way to understand it.

All the prospective spouses are not good enough. Thus, so many look right past all of them.

However, you are ignoring the quote marks around "not good enough". Keeping it simple, it's used to talk about things that people tend to say/believe, but aren't correct.

So the real meaning is:

All the prospective spouses are "not good enough" (speaker/writer believes "not good enough" is something people tend to say/believe and is incorrect). Thus, so many look right past all of them.