I really think that it is better to love and lose than to never love at all. For a number of reasons. For one, each time you enter a relationship and lose one, you grow. You learned to become patient with that person, you learned to love the person for who they are. When you are in love with a person you tend to be more able to adapt to things you might not be able to adapt to in other circumstances.
Love though it can sometimes hurt can make us feel really good. We are able to see ourselves through another persons eyes.
Sometimes people come into our life for a season. We may need them to be their for a specific reason at a specific point in our lives and they will help us get to the next level.
If we never experience these things we would be losing out on a lot!