Putin has threatened so called unfriendly states to pay in rubles or have its gas supply shut off. It has said it doesn't buy things for free and so isn't going to charitable with its energy.
Europe has kicked against this with Germany saying its being blackmailed by this move. What other choice does Europe has with Russia alone selling about 40% of energy to the world.
There isn't really anything Europe can do short term. We are dependent on Russia for gas, there is no real alternative we can find in a few weeks. Also these are long term contracts with Russia, we can't just cancel them overnight. Same goes for Russia, they need the western money and will not stop the gas flow. Both parties in the contract want the gas to keep flowing. Putins rational behind this move is strengthen the currency, via increasing demand for Ruble. The German chancellor Olaf Scholz already said they will only pay in Euro or Dollars, but this doesn't matter. Gazprom is creating new bank accounts that will directly change the euros or dollars into Ruble.