In the beginning of the play, we see a loving couple. Hermione is expecting their second child; Leontes best friend is still visiting; life is good in Sicily.
It is only when Leontes observes Hermione trying to get Polixenes to stay and she succeeds where he has failed that he becomes jealous and suspicious. What is curious about this is that what Shakespeare describes is a real mental illness which behaves exactly as described by Leontes' behavior.
The jealousy is unfounded and seems to come out of no where and the best friend is suspected. That Hermione and Polixenes are blameless doesn't matter.
The next step of this illness is to try to kill the one believed responsible, ie in this case Polixenes.
The next step is a depression which can last from days to years.
The confrontation between Hermione and Leontes is between Leontes unfounded jealousy and Hermione's innocence. Even when Apollo himself tells him through the oracle that she is blameless, he does not believe the truth but continues to harbor his anger ordering Antigonus to get rid of the his new born daughter.
Leontes becomes a tyrant. Paulina is the only one who stands up to his tyranny. In Act III, scene 2, she enumerates his unreasonable and foolish behavior.
Herminone on the other hand shows herself to be a woman of integrity and strength. Her speech in her own defense in Act II, scene 1, demonstrates this.
The reconciliation of these two in Act V, scene 3 is one of the most beautiful and magical scene in Shakespeare.