What does それすら来ないと言うこと means?


I was watching some Let's-players on YouTube, where I saw this sentence:

> それすら来ないと言うことは……きっと、よほどのことがあったに違いない。

I'd like to know what the first part of it means. Moreover, the entire meaning
of the sentence is still a little fuzzy to me.

For some context, here's the sentence before it:

> 「璃紗の、あの性格上……元気じゃなくても、相手に心配かけないように、無理してでも元気だって返事をするに決まってるわ」




This sentence uses the `AということはB((ということ)だ)` construction, which means "The
fact that A means B", "If A, then it means B", etc.

  * [〜ということ and just 〜こと](https://japanese.stackexchange.com/q/33759/5010)
  * [I'm having trouble translating this sentence](https://japanese.stackexchange.com/q/58953/5010)
  * [ということは… ということだ grammar](https://learnjapanesedaily.com/japanese-%E3%81%A8%E3%81%84%E3%81%86%E3%81%93%E3%81%A8%E3%81%AF-%E3%81%A8%E3%81%84%E3%81%86%E3%81%93%E3%81%A8%E3%81%A0-grammar-toiukotoha-toiukotoda.html)

In your sentence, A corresponds to それすら来ない and B corresponds to
きっとよほどのことがあったに違いない. それすら is just それ ("it") followed by すら ("even"). それ refers
to a 返事 from 璃紗. Note that すら can replace the subject marker が, just like は
and も. よほどのこと is "something very unusual/extraordinary".

> それすら来ないと言うことは……きっと、よほどのことがあったに違いない。  
>  Even one reply has not come...it must mean something very unusual happened
> (to her).




This sentence uses the `AということはB((ということ)だ)` construction, which means "The
fact that A means B", "If A, then it means B", etc.

  * [〜ということ and just 〜こと](https://japanese.stackexchange.com/q/33759/5010)
  * [I'm having trouble translating this sentence](https://japanese.stackexchange.com/q/58953/5010)
  * [ということは… ということだ grammar](https://learnjapanesedaily.com/japanese-%E3%81%A8%E3%81%84%E3%81%86%E3%81%93%E3%81%A8%E3%81%AF-%E3%81%A8%E3%81%84%E3%81%86%E3%81%93%E3%81%A8%E3%81%A0-grammar-toiukotoha-toiukotoda.html)

In your sentence, A corresponds to それすら来ない and B corresponds to
きっとよほどのことがあったに違いない. それすら is just それ ("it") followed by すら ("even"). それ refers
to a 返事 from 璃紗. Note that すら can replace the subject marker が, just like は
and も. よほどのこと is "something very unusual/extraordinary".

> それすら来ないと言うことは……きっと、よほどのことがあったに違いない。  
>  Even one reply has not come...it must mean something very unusual happened
> (to her).

