Ser vs estar in lesson 9.8

I have a question from lesson 9.8. It says "(we) were friends once" translated as "fuimos amigos una vez", the preterite of ser. This sentence implies that the friendship ended. Shouldn't the preterite of estar be used here?

¡Hola LisaL92!

Thanks for your question!

We only use estar for things that we know (or expect) to be changeable in nature - for example, for health, emotions, location, etc. We don't expect these things to remain steady. Relationships between people, on the other hand, aren't normally expected to be changeable - they are generally looked at as being steadier, more constant things, and so they are described with ser. 

So even though the relationship between two people has changed in this sentence (i.e. they were friends, but they aren't anymore), we wouldn't switch to using estar because the nature of being friends hasn't changed - it's still considered to be a stable quality.

I hope that this makes sense - it is a tricky concept to explain! :) It might be helpful to take a look at Lesson 8.5: SER and ESTAR Revisited, if you haven't done so already.

If you still have questions on this, just let me know!

Saludos,

Liss

I see.  So if you wanted to communicate that you were still friends or likely still friends (like maybe “we first were friends” or just we were friends then & still are) you would use eramos instead of fuimos?

¡Hola LisaL92!

Yes! :)

If you use the imperfecto and say Éramos amigos “(We) were friends,” you're showing that you were friends at the time being described. You aren't indicating a beginning or an end to this friendship - you're just saying that at that moment, you were friends. So in the present, you might very well still be friends.

If you use the pretérito and say Fuimos amigos “(We) were friends,” you're showing that there was a start and finish to being friends. This makes it very clear that you are no longer friends now, because the state of being friends definitely ended in the past.

Let me know if you still have any questions!

Saludos,

Liss