This quote by Billy Idol is a metaphor for the concept of a relationship. The phrase "rocking the cradle of love" implies that the speaker remains in a caring relationship and is looking after it. The expression suggests that the speaker is supporting and protecting the relationship, simply as one would rock a child in a cradle. The phrase likewise suggests that the relationship is fragile and needs to be handled with care. The expression also suggests that the speaker is devoted to the relationship and wants to put in the effort to make it work. The expression is a tip that relationships require effort and devotion in order to achieve success. It is a suggestion that relationships are not something to be taken lightly which they ought to be cherished and supported.
