Love certainly feels like an emotion; an incredibly strong one. But in the scientific community, the conservative definition of an emotion is a facial expression. Happiness, sadness, disgust, anger, surprise: these and the other basic emotions can be seen easily on the face. But drives are not linked with a specific facial expression.
A drive focuses our behavior on a goal, and lasts until that goal is fulfilled. Hunger is the classic example. When you are hungry, the goal is food. You remain hungry until you get food. You can be hungry for hours, days or even weeks in extreme circumstances. You will likely go through a wide spectrum of emotions as you attempt to find and eat the food. You may feel anger or dismay when your attempts to procure food are thwarted, contentment or even elation when you finally get to eat.
Like hunger, love is a drive. The other person becomes a goal in your life, and you may go through many emotions as you focus on winning him or her. We tend to identify love most often with euphoria, but that is hardly the only emotion we feel. Ecstasy, compassion, surprise, anxiety, anger, jealousy, despair: we swing like a kite from high to low, tied to another by this passion.