It's a good source of pleasure. It can help overcome fear of death. Everybody wants to be loved. It has many advantages, and it makes us proud. Priests tell us that love is the essence of religion, and doctors tell us that love is good for health.
Sex is another fine thing, and it's closely related to love.
We like to have sex with the person we love, especially if we are jealous. And if the person whom we love will accept us as partner in sexual play. If we are not loved anymore, and if we ourselves do no longer love, life becomes rather dull. I talk about the engineering of love, not a religion or mythology of love. As in any field of engineering, my interest is practical.