How long have you been married (for)? [duplicate]

Some personal observations that won't fit in a comment box. Firstly, as a rule of thumb it seems better to use such noun phrase Adjuncts of duration (i.e. those which occur with numbers, e.g. five minutes, three days, a year) with stative verbs, verbs that describe situations and not real actions:

• I've lived here three years.
• I've been in the marines five months.
• I've had this car seven days.
• I've known Ben three months.
• I've only owned this five minutes.

These usages are more common, I believe, in American English than in British English. However, in British English they seem massively improved if there is another preposition phrase after the duration phrase. One example is the word now:

• I've lived here three years now.
• I've been in the marines five months now.
• I've had this car seven days now.
• I've known Ben three months now.
• I've owned this ring five minutes now.

Notice that we shouldn't confuse these duration Adjuncts NPs with temporal NPs functioning as the Complement of a verb. Several verbs take such NPs as a Complement:

• I waited five minutes before leaving.
• I stayed five months at that hotel.
• The film lasted three hours.

Omitting the preposition is acceptable and commonplace in the US:

I have worked here five years.

and without a direct object:

The tree has been growing five hundred years.

EDIT#1

For very short sentences or durations without a specific value, it is more common to include the for

I suffered for years.

We tried for years to get pregnant.

rather than:

I suffered years.

We tried years to get pregnant.