Ser vs. estar for "eran muy felices"

Question

I am confused about the use of eran instead of estaban in this sentence below. I understand feelings to be impermanent states, for which we generally use estar. No one/no couple is usually happy constantly, all the time; they experience a variety of different, variable emotions. Is it the difference like saying, "We were a happy couple" vs. "we felt happy"? Gracias!
Ustedes ________ muy felices como pareja.You used to be very happy as a couple.

Answer

Good question.  Interestingly, I just came across the same idea in another lesson:  Cuando nos casemos, seremos felicísimas las dos.

Answer

My Grammar book [by Butt & Benjamin] implies that the customary use [in Spain] of 'ser' before 'feliz' can be regarded as an 'anomaly', i.e., it does not follow the logical rule [which says that 'estar' should be used if it describes a 'temporary or transitory state' or a 'condition']. Thus, there is little or no difference between "Estoy contento" and "Soy feliz"... The above book also mentions that [in Spain] you will usually see "ser pobre" even when that is referring to a temporary state... [in Hispano-America, on the other hand, you will often hear 'estar pobre' and 'estar feliz']

Answer

Hola Kirstie

The general rule says to use estar for feelings, but for some reason (not a logical one I'm afraid) in Spain we have a tendency to use the adjective "feliz" with ser more than estar, even when the situation is understood as a temporary state of mind.

What you cannot do is use "ser" with "contento". You always need estar with contento.

Saludos