what are the tragic elements in william congreve's way of the world?

Infidelity is a tragic element of the play. Mr. Fainall is a married man, but his closest relationship is to his mistress, Ms. Marwood. He plots to get money out of his wife's mother, Lady Wishfort, after finding out from his mistress that his wife, Mrs. Fainall, married him while in a relationship with Mirabell.

Describe the tragic elements in the way of the world?