A method of operating a first user equipment (UE) in a wireless communication system is disclosed. The method includes establishing two or more PC5 radio resource control (RRC) connections with a second UE by the first UE, and releasing an RRC connection for which sidelink radio link failure (SL RLF) has been declared among the two or more PC5 RRC connections by the first UE. There is a PC5 unicast link associated with the PC5 RRC connection, and the PC5 unicast link for which the SL RLF has been declared and the PC5 RRC connection has been released is indicated by a PC5 link identifier (ID).