no one knows, because love is an emotion, and everyone experiences emotions differently, albeit often similarly. there is a chemical component (not just endorphins but yeah them too), a sexual component, other components. everyone is unique. a lot of people can tell you what love is NOT, but no one can tell you definitively what love IS (though plenty of people will try). i forget who said (approximately) that in real love you want the other person's good, and in romantic love you want the other person. that's not definitive but it's a clue.

g