When to use 'had been' + past participle of the verb

I read the sentence below in a news article:

"The couple had been engaged since the summer," her spokeswoman said in a statement.

Why was "had been engaged" used in this sentence. Is it wrong to say "The couple have been engaged since the summer"? Is this sentence in passive voice so "had been + past participle" used?

PS: I read other questions on stackexchange about tenses, but I couldn't understand why was had been + past participle used in the sentence.

Without further context this is a little difficult, but one reason it could be written this way is that the couple is no longer engaged. To amend the sentence for clarity:

"The couple had been engaged since the summer," her spokeswoman said in a statement, "but now they have ended the relationship."

edit: I believe this is referred to as the Past Perfect Progressive tense (or Past Perfect Continuous)