head. His own nativity and jealousy also drew nails into the coffin.
Othello was told various lies and he jumped to conclusions and eventually *spoiler alert* kills his wife because of his jumping to conclusions. Iago did plant ideas, but Othello didn't have to jump to conclusions. Othello chose to assume things. I do in fact understand that if Iago didn't plant those seeds, Othello wouldn't have jumped to conclusions, but it was Othello who decided to jump to conclusions, not Iago. If he truly loved Desdemona the way he said he did, then he would have asked, but he didn't and just simply assumed she made a cuckold out of him and punished her for it. Yes, Iago is to blame, but not as much as Othello is. Iago is the cause as to why Othello jumped to conclusions, but he didn't force Othello to do anything, Othello chose to do everything. He was the one who chose to not trust his wife. He was the one to trust his servant over his wife. He just continued to assume everything Iago was saying was true. He never really wanted real proof. At one point, he did want proof. In 3.3, he demands proof from Iago and then in 4.1 he settles for Iago suggesting that the handkerchief Bianca had was given to her by Cassio who got it from Desdemona. He doesn't demand proof of this exchange, he just assumes that "honest Iago" is telling the truth. He is just too ridiculous and too trusting.
His nativity and his inability to trust Desdemona is what made Iago's plan work so well. I personally think Othello was extremely naive when it came to his relationship with Desdemona. Based on what I've read and my own personal opinion, I don't think Othello knew how to properly love his wife or what a relationship like that is supposed to be like. I think he just had a very simple understanding of what marriage is supposed to be. He even said that he loved her because she pitied him (1.3) which is definitely not enough reason to get married to someone, but he had a very naive idea of marriage. It is supposed to be based on trust and I don't think he truly understood that. He shows it every time he believes Iago over his own wife. He literally end his wife's life because he trusts Iago more. Also, whenever Othello asked Desdemona about the possibility of her being unfaithful, he'd always be extremely rude about it because of Iago's claims and suggestions further adding to the fact that Othello trusts Iago more. Othello just did not trust Desdemona. The thought of Desdemona cheating on him puts him into an epileptic fit (4.1), which to me indicates he found it to be believable and further indicates he did not trust his wife.
Othello was a naive man, who put his trust into the wrong people. He assumed way too much and he didn't trust his wife enough and in the end, it is what lead to his downfall.