What roles do the Duchess of York, Duchess of Gloucester, and Queen Isabel play in King Richard II?

The Duchess of Gloucester adds the richness of human
emotion to the play. She becomes a widow  when her husband dies, but their love is one
based on love rather than necessity or politics, and she is devastated by his loss. In
Richard II, the Duchess of Gloucester's character imbues the play with the recognition
of what war and death do to a family. In her situation, she loses a husband—her dearest
love. Shakespeare shares the sense of loss for a spouse, which is very different from
losing a parent, child or friend. As the reader, we will gain a clearer understanding of
what love is by comparing and contrasting her sense of loss with that of other
characters in the play. Lastly, the Duchess of Gloucester is the character that sets the
mood of the play. As she speaks later of her loss, this will serve to continue the
ongoing sense of loss in the plot development.

The Duchess
of York exemplifies the love for a child. In supporting her son, she must make a clear
choice between flesh and King. This would have been an enormous undertaking for a
parent, especially a mother, in Elizabethan times when devotion to one's monarch
overshadowed all else. Her love is unconditional: even though her son has aligned
himself with men who have attempted to kill Henry Bolingbroke. The complication to this
love is that her son is complicit in the plot to kill Bolingbroke who is cousin to
Richard II (and will one day be England's King Henry IV). This is outright treason; and
in defending her son, she defies her husband who is, above all, loyal to King and
country.  However, the Duchess of York she cares nothing for politics where her son is
concerned. It creates a chasm between husband and wife as the Duke cannot afford to
place his child above his politics: and in honor, would never think to do
so.

Queen Isabel is the wife of Richard II.  The Duchess of
Gloucester undoubtedly loved her husband; this kind of devotion is also seen with Queen
Isabel. And the Queen stands in stark contrast to the Duchess of York: for the Queen
supports her husband in all things, even when his cause begins to falter. Another way
she is similar to the Duchess of Gloucester is her dramatic purpose in conveying the
dark mood set at the beginning of the play. It is equally important that it is through
the Queen that Shakespeare provides the audience with foreshadowing that some horrible
event awaits—specifically Richard's murder.