The relationship between Desdemona and Othello was conflicted from the very beginning. This was the case because no one could understand or accept the mutual love that was shared between them. Iago knows how strong their love for each other is, and he uses this as his means to seek revenge on Othello. He does this by breaking the mutual trust that is initially present in their relationship. Although the relationship between Cassio and Desdemona is honest, the fear of her dishonesty consumes Othello's mind and leads him to do things that are completely out of character -- things he would never see himself capable of doing in a right frame of mind.
The thought of love often clouds our ability to think logically in the midst of our everyday lives. So although love is often associated with the positive aspects of life, including the things that we desire most, it can lead to the fear of loss and deception. As Othello has presented to us, love can lead to destruction in the sense that it is vulnerable and easily influenced by outside forces present in the world. Although love in its purest form is beautiful and innocent, the evil that is found in the natural world has a tendency to come between that love and to taint it to the point of no return. In reading the play, we uncover and expose the dark side of love, watching Othello subject himself to the influence of the outside world and allowing evil to overcome his heart and destroy his sincere love for Desdemona.