We are born sinners, and when we are sinners, we are programed to operate according to our sin. When we have a "piece" taken away (an old sinful habit), we begin to understand that we are not made to be sinners. But we all struggle to release our sins, sin is fun. We enjoy sin. Through the struggle of following Jesus and abandoning our sin is what helps us find rest.
"This deception I called love" basically means that we can love anything and give ourselves to anything. If it's not Jesus, we decieve ourselves and call it love.