There is no "right" here.
Steven tried to take responsibility, but he was so intent to just martyr himself that he forgot how much people care for him, how much they did to keep him around and safe.
And he just shoved them all aside, denied them any say and sacrificed himself without allowing anyone to help, to defend him, to honor their allegiance.
By this point he has realised he has responsibility for everyone, but not that everyone wants to take as much responsibility for him.
He essentially brought the whole gang to a fight, then told them to stand back and let the others kill him.>hey all my moms and gf, I know we fought for years and you did all you could to protect me, but let me just ho behind your back and say that's all meaningless now, have fun living with a Steven-shaped hole in your hearts
He thinks he protects them, which is not wrong.
But in doing so he just takes their agency from them. He renders them powerless and desperate to be the big hero. And then he just comes back home and acts like it was not utterly suicidal what he did.
From his perspective he was selfless, but that really is a self-centered point of view. He has to protect them all. He does it all alone. From their point of view he took from everyone the chance to stand and fight. Especially Connie feels betrayed. And she hasn't even fought a war in his mom's name and sworn to keep him safe for her. But she was supposed to have his back, jump all the way into the jaws of hell with him. And then he went alone, told her she was not to go with him. Just a frail human. Not good enough. He does not see it that way, but she does.
This is a reflex you see in warriors or soldiers. When they fought together for a long time and believe in their cause, they get upset when the commanding officer or national leader declares capitulation before they see that defeat is inevitable.
But Steven does not see that. He wanted to know his family is safe, but in doing so he betrayed his unit.