Learn English – Difference between “had been …-ing” and “was/were …-ing”

Both forms express perfect aspect, that is to say they express a state resulting from an earlier event. The has/have been form is known as the present perfect and relates what has happened in the past to what is happening now. The had been form is known as the past perfect and pushes the events further back. It relates what happened at some time in the past to the situation at some other time in the past. If I say I have been at work for eight hours, I describe the position now. If I say I had been at work for eight hours, I describe the position as it was at some earlier time.

The first two are grammatical. In the first, married is the past tense of marry, and is here used intransitively.

In the second, they were married is a passive construction, and married is the past participle of marry. Although it is passive, the agent is not mentioned, but we can reasonably assume that they were married by a priest, or by a government official.

The third is ungrammatical because the past perfect construction describes a past event that precedes another. It is clear in this case that the wedding took place only after they had been engaged, and not before.