I am a firm believer of the whole "Zoro's biggest fear is failure but especially failure at protecting his fellow and if someone gets seriously hurt, his first instinct is to blame himself for not being there (ex., Ace's death and Luffy getting traumatized because of it) 'cause next to Luffy, he is the most responsible for the crewmates well-being (and because he thinks his love language is just fighting, yeah).
I heard someone else call this "The Anxiety of Strength" which is a name that goes hard and does a good job explaining this concept but also.... When I write it out like that, it sounds like he basically just has a specific adaptation of Eldest Daughter Syndrome, doesn't he?...