Othello ha issues trusting about whether or not Desdemona is actually cheating on him with Cassio
IV.i.226-270 Desdemona : I'm happy about that. Othello : Oh are you really! Desdemona : My lord? Othello : I'm glad you're insane enough too admit it in front of me. Desdemona : Why, sweet Othello - Othello : You devil! Desdemona I haven't done anything to deserve this
Person vs Society
IV.i.110-115 Cassio : The poor thing! Othello : He's laughing already Iago : I never knew a woman who loved a man so much. Cassio : The poor thing I really think she loves me Othello : Now he denies it a bit, and tries to laugh it off. Iago : Have you heard this Cassio? Othello : He's asking him to tell the story again. Go on tell it.
Person vs Person
The scene of Iago thinking about Desdemona cheating on him with Cassio is an internal conflict. This is because he doesn't know whether he should trust Iago and his accusations. However, when he provides evidence to support his claim he turns into a very diabolical person. This leads to him acting immoral and slapping Desdemona which makes people question how good of a person he is.
Person vs Self
The scene of Othello slapping Desdemona is an external conflict. This is because his reputation may go down from Lodovico being a witness. Not only is it immorally wrong to slap your wife, he also does it in front of Lodovico her cousin. Though he feels he has reason for this since he has "proof" of her cheating it still doesn't justify his actions. At the end of this Lodovico is very shocked at his actions and doesn't understand why people look up to him and since they're cousins he may report these news to the public.
Othello has a conflict with Cassio. He is astonished that after all that they've been through he would go turn his back against him and have an affair with Desdemona. When he's observing this he mutters under his breath a lot about how Cassio thinks he's won but this is only the beginning. This can foreshadow that he will kill Cassio which also propels the plot.