Has seeing the horrors of the Ukraine war made you want the west to stop it and force a surrender? More horrors don't make people want less war. If anything, it may be the opposite. People pretend to be anti-war right up until there's a war and then suddenly it turns out they're actually anti-losing-the-war.
I want less war. I'm against attacking other countries, but totally in favor of defending yourself if you get attacked. Those aren't contradictory statements.
That sounds noble until it doesn't work in reality and people always find reasons to justify wars. If it was so simple, it would be easy for most people to get on board with and most wars would end.
For example, do you agree that Britain's and France's appeasement of Germany before WWII was the right thing because an attack wouldn't have been self-defense? Or, what about attacking another country to help defend an ally who's being attacked by them? That's not defensive, so I guess it's wrong by your standard for any other country to defend Ukraine. What about defending them by supplying arms and soldiers? The line gets blurry fast.
How about re-taking some recently lost territory? Is that wrong? For example would it be wrong for Ukraine to attack Russia to regain its eastern areas that Russia took at the beginning of the war? Or for Russia to retake any other parts of the soviet union? How about either North or South Korea attacking the other? If everybody opposed such non-defensive wars, they would be severely disadvantaged to a country that incrementally takes pieces of their territory in a ratchet effect.
What about "liberating" the people of another country from a brutal dictator? I'm sure you'll oppose this because it's like Iraq or Syria, but is there really no case where it's justified? Not even Pol Pot's Cambodia where it might have saved a quarter of the population from death it somebody had intervened?
Surrendering to an aggressor will let the aggressor get what they want, hence making war more appealing. So it's coherent for anti-war people to resist and make it as hard as possible for an aggressor. Even Gandhi justified defensive war.