There are probably layers of nuance behind this.

Blocking the sale of Russian oil forced the EU to purchase US oil at a premium. Not conducive to ending the war from the US perspective.

Continued combat in Ukraine requires the purchase of US armament. Not conducive to ending the war from the US perspective.

The EU being a supplicant strengthened the US hand in trade negotiations. Not conducive to ending the war from the US perspective.

Probably much more that we don't know about driving the current situation.