How does 「信じられている」 differ from 「信じている」 in this sentence?


> 仲睦まじい様子の男女二人連れと、幾度もすれちがう。この中で、どれほどの人たちが、いま一緒にいる相手のことを、
> **この人しかいないと信じられているのだろうか。**

This is a line from 「私の男」by 桜庭一樹著

When I searched for the translation online, I found this one [![enter image
description
here](https://i.stack.imgur.com/i1gJ4.png)](https://i.stack.imgur.com/i1gJ4.png)

> I wondered how many of them believed that the person next to them right now
> was the only one. Each person passing by might have his or her own
> circumstances.

[Source](https://www.proz.com/translator/1126210?text=English%20to%20Japanese%2C%20Japanese%20to%20English%20translator%20specialized%20in%20computer%20technology%20and%20general%20topics)

It does not seem to differentiate between 信じられている and 信じている. What is the
difference between この人しかいないと信じられているのだろうか and この人しかいないと信じているのだろうか and what
nuance does former have over latter?




This is the teiru-form of 信じられる, which has a potential meaning here ("to be
able to believe"). So the difference between 信じている and 信じられている is basically
the same as that between 歩いている ("is walking") and 歩けている ("can be walking").
Thus the literal translation is "I wonder how many of them can be believing
...", but the translator may have thought this sounded redundant as an English
sentence.




This is the teiru-form of 信じられる, which has a potential meaning here ("to be
able to believe"). So the difference between 信じている and 信じられている is basically
the same as that between 歩いている ("is walking") and 歩けている ("can be walking").
Thus the literal translation is "I wonder how many of them can be believing
...", but the translator may have thought this sounded redundant as an English
sentence.

