Twitch-
While people have different ideas on what love actually is, to me it's caring for someone deeply. We can tell it exists, because we have evidence all around us of people treating others with care, even giving their own lives to save others in some cases. Love is a universal concept- we don't have people in America thinking love means one thing, and people in Iran thinking it means something else (like, you know, gods!).
If someone said they loved you, then punched you in the face, would you still believe they loved you? Or would the evidence speak against that?