Iraq and recent Afghanistan are not good examples for your argument, dude. The US had boots on the ground in both those places as an occupying army after taking out autocratic governments and trying to prop up fledgling democracies. They were the Russia in those situations (ignoring the morality/ethics of the respective wars).
Ukraine is a war with no direct military involvement from the west. No troops on the ground, no planes in the sky, nothing. So I don’t see why you keep talking about being involved in a ten year war? The west is financially backing Ukraine by supplying arms for them to fight this war. If anything, your examples support my point. Afghanistan 1.0 and 2.0 ended with first the Soviets defeated, and then the West leaving. Iraq is a little more murky, but no one wants the US there anymore. Even North Vietnam defeated the US in the end with Soviet support.
Your “average” American that doesn’t want to continue backing Ukraine long term, is the Tucker Carlson, Trump supporting average, which isn’t the average at all in point of fact. So let’s not pretend that it is. There is currently no majority that is anti-supporting Ukraine. And even the GOP is split on the issue.