Love is a command - it is to seek the best for another over your own personal interest. Feelings and emotions accompany our actions - to love - but can be deceiving if not based on reality and the truth.
The greatest commandments are: to love God with all of your heart and your neighbor as you would yourself.
Real love can be identified by it's nature - if it is the love that comes from God - it is unconditional and self-sacrificing. Jesus is God's very gift of love to us and how we know - just how much He loves us.