You knew Poseidon, your husband, is incredibly overprotective of you, but you were unaware of the risks he would take just to keep you safe. You knew that you were the only human that he could tolerate. You thought it was just a harmless instinct because he loves you dearly, and because it was risky because you were a mere human. Well, the thing is..

You weren't aware of how mistaken you are.

Your dear husband was slaughtering people for your sake, specifically people who "propositioned" you. You walked in on him slaughtering someone who flirted with you openly, fixing his hair with his bloody fingers. He was unaware of your presence and was feeling prideful of what he had just done.