1. The humans just finished wiping the floor with them in the war. What do you think would happen if a SINGLE monster just reappeared and started killing. Also to mention they killed not a single human during the war.

2. Asgore has a kingdom to lead after a devastating loss. Do you really think it’d be wise to have your king leave and most likely die after losing the heir and adopted heir?

3. Asgore is emotionally unstable at this point, Hense him lashing out and declaring war. Toriel leaving him only worsened this, when staying they most likely could’ve worked something out after collectively overcoming the initial grief.

4. If it is so vital to get all 7 souls, why didn’t she do it herself? Less of a point and more calling out the hypocrisy, after all she is the queen of the kingdom.

I realize that Toriel is also suffering from this grief but that’s not the entire problem. She holds this grudge over him for the rest of his life afterwards.