Peter denied that he knew Jesus, which Jesus foretold.
Later, Jesus predicts that Peter will follow Jesus in places that he won’t want to go to, but that he will go to. Peter will go this time. This time he will not deny Jesus, but will follow him in places that were uncomfortable and uncertain.
Peter went because of love for Jesus.
At times, love means going where one doesn’t want to go for a mission greater than ones self.
If Peter loved Jesus, he would spread his master’s message–Jesus said he offered eternal life and other people should know it–even if going to spread the message was out of Peter’s comfort zone.
The lesson in love is that love for Jesus can take one out of the comfort zone, through thick and thin.