Hello....there is no war between army of one country versus army of another country in Ukraine. It is strictly hit and run tactics by Ukrainian forces. Such guerilla wars do not produce quick victories. DO you remember how long United States fought in Vietnam? Again it was hit and run guerilla tactics by Viet Cong which made the conflict go on for like ever.
The Russians are getting their butts kicked, yes. But they certainly thought they were going to waltz right in and dictate terms.
I don't carry water for Ukraine. It's probably full of corruption. But so is Russia and Putin is a thug and a bully, and I hate bullies.
The VietCong did not defeat the U.S. military. The VC and NVA were decimated after the ‘68 Tet offensive but General Giap was convinced (correctly) that the war could be won in the UnitedStates public arena.