This paper propose a dynamic mathematical model of love with the Fourier series function as an external force. We also investigate the periodic doubling including 1, 2, 4 periodic motion, chaotic attractor and limit cycle in the love models based on Romeo and Juliet with the Fourier series function as an external force, using time series and phase portraits. To show the nonlinear phenomena using time series and phase portraits, we vary the parameter value with the Fourier series function as an external force.