What does "The moment I’d been sure would come." mean in "Swimming in the Dark"?

Question

I would like to know what "The moment I’d been sure would come." means in the following sentences:

I wiped my face and thanked her.

She stood still, looking down at me.

‘You love him, don’t you?’

She said it softly, neutral, almost as if it wasn’t a question. I closed my eyes to say ‘Yes’, and looked at her, saw that she’d understood. Then a shadow flickered across her face, a trace of doubt. The moment I’d been sure would come. She remained still and looked at me intently, scanning me for reassurance, begging me for it with her eyes.

‘You and Janusz …’ she began, but I interrupted her.

‘He doesn’t know,’ I said, slipping the wet ball of tissue into my pocket, trying not to tremble, to keep my voice steady. ‘Don’t say anything to him.’

She nodded, her fear dissolved. ‘Of course not,’ she said, trying to cover her relief. ‘I won’t.’

• Tomasz Jedrowski, Swimming in the Dark, Chapter 7

In this novel which is set in the 1980's in Poland under the socialist regime, where homosexuality was socially unacceptable, the protagonist Ludwik left Poland in 1981 to live in the United States of America. And he remembers what it was like back then in Poland, where he decided to leave the country after trying hard to stay in the country. (The main reason that Ludwik decided to leave the country was the fact that his lover Janusz constantly tried to straddle between Ludwik and a girl named Hania, the daughter of some high Party officer. But Hania didn't know about their relationship.) But the Passport Bureau wouldn't give him the passport, blackmailing him with the fact that he was a homosexual. So Ludwik took another route, by visiting Hania's house and telling her about his situation and asking her for help so that he could get the passport. But Hania said she needed to know what it was that they were blackmailing Ludwik with, in order to know how to best approach the situation, so Ludwik came out for the first time in his life, confessing that he was a homosexual. To his confession, Hania asked him whether he loved Janusz, and Ludwik said "Yes." At this, Hania began to doubt the friendship between Ludwik and Janusz for the first time, wondering whether they had been actually lovers, not friends.

In this part, I wonder what this boldfaced part means. I thought that it was a complete sentence, like this:

The moment (subject) [that] I’d been sure would come (verb).

And guessed that he was saying that the moment (probably the moment he had been expecting that Hania would ask about his relationship with Janusz) would come now.

But is it really a noun phrase, everything after "the moment" modifying "the moment," like this?

[This was] The moment (noun) [that] I’d been sure [that it] would come (modifying phrase).

Answer 1

Look at the wider context.

Then a shadow flickered across her face, a trace of doubt. The moment I’d been sure would come.

We use the definite article "the" to refer to something unique or something which has already been mentioned.

Your sentence refers to "the moment". A 'moment' is not unique, so "the moment" must have already been mentioned. You'll see I have highlighted that the previous sentence begins with "then" - that is the moment.

So, the narrator had always been sure that 'she' would begin to doubt. When they saw the flicker of doubt on her face, they knew that moment had finally come.

Answer 2

Yes, this is a sentence fragment. The rest of the sentence is implied:

The moment I'd been sure would come [had arrived].

or

[Here it was,] the moment I'd been sure would come.