An oft-cited piece of evidence for this possible motivation is the scene wherein Iago and Othello initiate a pseudo-wedding ceremony. To each other.
Othello: *kneels* In the due reverence of a sacred vow
I here engage my words.
Iago: Do not rise yet. *kneels*
Witness, you ever-burning lights above,
You elements that clip us round about,
Witness that here Iago doth give up
The execution of his wit, hands, heart,
To wrong'd Othello's service! Let him command,
And to obey shall be in me remorse,
What bloody business ever.
Othello: I greet thy love,
Not with vain thanks, but with acceptance bounteous,
And will upon the instant put thee to't:
Within these three days let me hear thee say
That Cassio's not alive.
. . .
Iago: I am your own for ever.