>>3827964
>maybe he was right but he essentially betrayed their trust and their hopes in that situation and decided what was best for them after making a different choice.
This is typically referred to as a "necessary evil". While "evil" would definitely be a harsh word in this context, the general idea is that it's sometimes necessary to do a small bad thing in the name of accomplishing a greater good thing. In this case, emotionally hurting their friends by suddenly leaving them to go sacrifice themselves is a minor injustice compared to the emancipation of an entire race. A minor injustice committed in the name of a greater justice.
It's an injustice that they're all in that situation to begin with. The human-monster war should never have happened, monsterkind never should have been sealed underground, Asriel and Chara never should have died, the human souls never should have had to be harvested, etc. Monsterkind's imprisonment is an injustice, but it's not going to be made right without the souls to break the barrier. In this context, it takes an injustice to right another injustice.
Besides, if Clover's soul really is built around the concept of justice, I'm not too sure how happy they'd be in the first place, knowing they have the power to put monsterkind one step closer to freedom but choosing not to. That, and knowing that some other human's going to have to pay the piper if they don't.
