Europe's sanctions against Russia are not driven by US interests. You can see this clearly by just how much the Russian government despises European leaders. America has never really cared about Ukraine or Russia and Biden didn't actually provide much support to Ukraine until they started winning. Europe generally is also more invested in and holds stronger support for international law (not the "rules-based international order" like most of the anglosphere) even if they don't always uphold it.

The war in Ukraine was of America's making, but Europe has to bear the consequences of it (as with everything America does). In that vein, since America started the war in Iran, Europe likely will have no choice but to start buying Russian gas again.