After Asgore declared war, Toriel was disgusted with his actions and left the castle. She locked herself in the Ruins, leaving behind her title as Queen. It may seem like Toriel was abandoning her people and Asgore, but it was her best option for a number of reasons.
The monsters support the War
While Toriel was against the war, she may have been the only one who felt this way. After Asriel was killed by humans, the people lost hope. Asgore’s declaration of war and promise to destroy humanity and exact revenge brought hope back. The people supported Asgore’s war against humanity.
ASGORE | NEUTRAL ROUTE: I remember the day after my son died. The entire underground was devoid of hope. The future had once again been taken from us by the humans. In a fit of anger, I declared war. I said that I would destroy any human that came here. I would use their souls to become godlike… …and free us from this terrible prison. Then, I would destroy humanity… And let monsters rule the surface, in peace. Soon, the people’s hopes returned.
If Toriel had challenged Asgore, she would have been denying the people their hope. The monsters may have even felt betrayed by her, a possibility shown in some of the neutral endings. She would be the queen who defended the humans that killed Asriel and Chara. To take away the new hope from the monsters would be to make Toriel the bad guy.
If Undyne is killed in the neutral route, the people start a rebellion to overthrow Toriel. Instead of trying to stop the rebellion, Toriel peacefully resigns and returns to the Ruins. She isn’t the kind of ruler that would force other monsters to see it her way, and frankly, even if she did try, it’s unlikely the rallied monsters would have listened.
Furthermore, it’s because of this hope that even Asgore is unable to stop the war he declared.
ASGORE | NEUTRAL ROUTE: Truthfully… I do not want power. I do not want to hurt anyone. I just wanted everyone to have hope…
She tries to save the humans from Asgore
After she left the castle, Toriel locked herself away in the Ruins. Toriel was not able to stop the war Asgore had already declared, so she tried the next best thing. She tried to keep the humans safe from Asgore.
It’s unknown how the other humans left the Ruins. Maybe they snuck away, or maybe they were able to convince Toriel to let them go. Either way, all the humans wanted “to leave so badly.” The fact that they did leave and die is not Toriel’s fault.
While the other humans’ stories are unknown, it’s clear that Frisk is determined to leave even when Toriel tells Frisk how dangerous the underground is. Frisk was likely the first human Toriel tried to stop by force. If the other humans had been given the chance to defeat Toriel and were still killed by Asgore, Toriel may have not given Frisk the chance to prove themself.
Toriel could have kept Frisk from leaving by destroying the door without hesitation, but she still gives Frisk the chance to prove they can survive. She even holds back when Frisk is heavily injured and then finally gives up to Frisk’s determination.
Toriel did want to save the humans, but forcefully locking them up would not have been the answer. Given that humans are far stronger than monsters anyway, desperation could have driven a human to hurt Toriel in order to leave. Even in the neutral route, it’s easy for Frisk to kill Toriel once she lets her guard down.
She is NOT obligated to take care of Asgore
After the deaths of Chara and Asriel, both Toriel and Asgore were hurting. However, Asgore’s pain was destructive – he declared war on humanity, promising to kill any human who falls into the underground.
Asgore may have acted out of anger, but that doesn’t make it Toriel’s job to take care of him. Toriel was a mother who just lost her two children. Her husband declared war that will result in more death – more specifically, the genocide of the entire human race. Her people were given hope from this war and supported it. Toriel was in no position to take care of her husband’s feelings when she was suffering from grief and betrayal.
Many people mistakenly believe it’s the wife’s job to take care of her husband and tend to his needs, but this should never be the case. Toriel had every right to get away from her husband and the people that condoned a war as a form of hope. Knowing that not even Asgore could take back this war, Toriel had no place in a kingdom that wanted bloodshed.
She NEVER condones sacrifices
There is a common misconception that Toriel condones sacrifices because of her dialogue upon seeing Asgore.
TORIEL | PACIFIST ROUTE: If you really wanted to free our kind… You could have gone through the barrier after you got ONE SOUL… …taken six SOULs from the humans, then come back and freed everyone peacefully. But instead, you made everyone live in despair… Because you would rather wait here, meekly hoping another human never comes.
This is not Toriel proposing an alternative plan, and this is not evidence of her thinking sacrifices are fine. The purpose of this dialogue is to answer an unspoken question – “Why didn’t Asgore go get more souls after obtaining one soul?” After all, even with one human soul, Asgore would have become a powerful monster “with unfathomable power” like Asriel was. With Asgore’s resolve to destroy humanity and the power of a human soul, Asgore could have easily retrieved six more souls. The monsters even know that Asriel had the power to destroy the humans who attacked him; Asriel just chose to not fight the humans. Despite this, Asgore chooses to make his people wait in hopes that he would never have to fulfill the promise he made. Toriel’s chastising of Asgore’s shaky resolve is an in-game acknowledgment of what was almost a plot hole – Asgore chose to wait for the souls despite it not being the most pragmatic option.
Even though Toriel allowed Frisk to leave the Ruins, she changed her mind and went after Frisk to stop them from killing Asgore. She is steadfast in her belief that no one should be sacrificed for another’s freedom. She values the lives of both humans and monsters. This is evident in both the pacifist and genocide routes.
Conclusion
tl;dr:
The monsters support Asgore’s war
Asgore is unable to put a stop to the hope-giving war he declared
Toriel never forces her kingdom to share her views on non-violence towards humans
Toriel tries to keep the humans safe from Asgore in secret
Toriel values all lives and never condones sacrifices
Of course, Toriel is by no means perfect. She has complexities and flaws – it is her unwavering belief in humans that ends her in some neutral routes and the genocide route. Regardless, leaving the kingdom was all she could do in the face of a war that would put monsters at risk and end in the execution of every human, including those not unlike the child she was still grieving for.
A Glitch Named Anti 