made any advancement on the Western Front. The Germans were pretty well dug in. On the Eastern front, the Russians were in all-out civil war so the Germans wouldn't have to worry about that anymore and could focus on the west.

You're right in part though that part of the reason for Germany's surrender was because there wasn't a real path to victory. The US joined and had fresh legs bringing almost limitless manpower and resources. A luxury that the Germans didn't have