There are no legal regulations with regard to finances for cohabiting couples or for communal living of any kind.
For this reason it is urgently recommended that you set up an inventory and conclude a cohabitation contract that
also regulates financial issues. 
In the case of joint acquisitions (e.g. property), a contract should regulate what happens to joint possessions in the
case of a separation. As a cohabiting couple you should not invest your wealth in joint accounts.
Contracts should always be concluded in writing. Cohabiting couples have no claims to benefits for surviving dependents.
However, funds exist that provide benefits for cohabiting partners above the prescribed legal minimum. It is worth checking in each individual case and, if necessary, to have your partner confirm your entitlement to benefits in writing.