What is the name of this grammatical structure? Cleft sentence? Noun clause? It was at that moment that he realized he'd fallen for her. It wasn't until two weeks later that he realized his feelings for her could damage him.
'That' appears to be used as a conjunction. I don't know if there is a specific name for this. "It was at that moment" and "He realized he'd fallen for her" are both complete sentences (although the first one seems incomplete out of context). 'That' connects the two to indicate the second sentence occured in the past. Maybe there's a technical term for it, but it's correct regardless.
It's an awkward construction, whatever it's called. My brain wants to simplify the sentences: At that moment, he realized he'd fallen for her. Two weeks later, he realized his feelings for her could damage him.
I myself suspect they are cleft sentences: https://dictionary.cambridge.org/grammar/british-grammar/cleft-sentences-it-was-in-june-we-got-married But I'm a bit confused because they can also be noun clauses.
The 2 parts are just reversed from how they'd normally be. This would be the more usual construction: He realized at that moment that he'd fallen for her. The second one actually is the least strange like this: He realized two weeks later that his feelings for her could damage him. But it would also work like this: Two weeks later he realized his love for her could damage him. It's a little strange each way. mostly because of the clumsy wording of He realized his love for her could damage him. Two weeks later (in it's various configurations) is a clause or a phrase (I'm not good with memorizing the names of these things) that can go in various places. The main sentence (subject, verb, object) is contained in 'he realized his love for her could damage him'. The subject is he, the verb is realized, and the object phrase is 'his love for her could damage him'. That's how you know all the rest is a separate phrase or clause. It functions as a unit and can be moved around without changing the meaning. It could be boiled down to a tighter sentence by removing the 'he realized' (one of those weasel phrases that means you're shifting the emphasis from the action to someone realizing something about the action). Then the main sentence becomes His love for her could damage him. This way the subject phrase is "his love for her" (Love being the direct subject), the verb is could damage, and the object is Him. It helps a lot to learn how to break down sentences like this, looking first for the subject, the verb and the object (if there is one). Once you've identified them everything else is a lot easier to place.
It's a technique called extraposition. You've shifted the idea to the right and left an empty pronoun (it) filling its space. That "it" is called a dummy pronoun. It doesn't really refer to anything. It is a good day to die. Here's a simple statement. It's a stative sentence that has no action. It just explains the state of something. (The state of IT equals A GOOD DAY TO DIE.) But the "it" starting it doesn't really refer to anything. Now you can force it to with revisions (e.g., Today is a good day to die.), but that doesn't change the fact that nothing was done on the paper in this draft. "It" points at nothing. It's just empty filler that holds the place of the subject. It was at that moment that he realized he'd fallen for her. So you have the subject on the left (dummy-pronoun, it's filler), "was" acting as an equal sign, and a quality assigned to the subject, so the long red phrase is acting like an adjective. It == he loves her So, basically the above is what you're saying. But "it" doesn't exist. It's just pretending to be a subject. Why? Because you wanted to shift emphasis. You wanted this big idea said and wanted the subject to point at it because it's extra important. You could have said this: At that moment, he realized he'd fallen for her. And that says the same thing, almost. IMO, there is a subtle difference. (Existential there! It does almost the same thing as "it" used as a dummy-pronoun/subject. I'm getting off subject . . .) Anyway, the difference is the emphasis on timing. If you just write it as "At that moment, he . . ." then you are stressing the moment. The revelation is still the love, but it's described as being important to the moment. If you lead in with a dummy-pronoun, then you are stressing the revelation as a whole. The timing is swallowed up in the revelation and that "singular moment" isn't what you're focusing on. It's the love that he discovers in the epiphany of the moment that you want to emphasize. They both come as one. That's just an IMO thing. Anyway, the point of a dummy-pronoun is to shift the sentence so that emphasis falls in a different way. It is grammatically correct, though it's slightly informal. It pulls far, far away from the MC into high narration. Only the narrator can say something so grand about the moment. The "It wasn't until . . ." sentence is of course the same construction, just with a "not" slipped in. Here's some links because you shouldn't trust yahoos on message forums. haha. I remembered most of this because I've been looking at existential-there and its tricks with singulars/plurals. Still, here's good sources. (L@@K. See that "here's?" That's wrong, but it's what I've been researching, that informal singular . . .) https://dictionary.cambridge.org/us/grammar/british-grammar/dummy-subjects https://www.thoughtco.com/extraposition-grammar-term-1690626 You could shift emphasis more if you wanted. It changes the flavor again. It was at that moment that he realized. (a one line setting description.) He loved her. There's a strange trick! You end that first line on what's usually a transitive verb. Its tension falls forward. This is fiction, not an essay. You have options. Many of them are stylistic and bend the grammar to the point of breaking. Just make sure you come back to a safe baseline.
My first thought was "compound sentence". I looked it up and seems they might not quite fit. Nor do they seem strictly "complex sentences". Though it appears one may have complex compound sentences, with various combined elements. My head's still spinning.
https://www.grammar-monster.com/glossary/adverbial_clauses.htm https://www.albert.io/blog/adverbial-clauses/ https://englishsentences.com/adverb-clause/
