When is it acceptable to whine?

Whining is never acceptable. Complaining is, but that requires actually being open to solutions.

When you are alone.

Anytime Monday to Friday between 9am and 6pm

In your own time

When dhining. I just can't decide whether to have red whine or white whine.

in italy, as in "when in rome"! any OTHER form of "whine" is ALWAYS unacceptable!

Only if you are a donkey or a horse!