Final answer:
Cassio and Desdemona did not sleep together; the false accusation is a result of Iago's deceit in Shakespeare's 'Othello'.
Step-by-step explanation:
No, Cassio and Desdemona did not sleep together. The play 'Othello' by William Shakespeare explores themes of jealousy, love, and betrayal, with Iago planting the seed of doubt in Othello's mind about Desdemona's fidelity. Othello is led to believe that Desdemona has been unfaithful with Cassio, which is not the case. Their alleged affair is a central part of the tragic misunderstanding that drives the plot of the play. Desdemona remains faithful to Othello throughout the story, and any suggestion of an affair with Cassio is purely the result of Iago's manipulation.