How do you know if you're in love?

there have been many times when i thought i was in love but i wasn't, actually, i contemplated this same question myself recently after falling in love, this time i know i'm in love. the best way for me to describe the difference between thinking your in love and actually being in love is fear. when you think your in love you are afraid that your partner doesn't love you the same, or that your partner will leave you, you don't want to believe it but you still think it. i'm not talking about being afraid for your partner's life, that's completely normal, if you care about anyone you'll fear for them. when you're in love you are no longer afraid of them leaving you, and you never doubt their love for you. i suppose the best way to describe this would be it's the difference between being afraid OF your partner and being afraid FOR your partner. at least that's my belief on the matter.