I love you
What is love? I'm fairly confident that is a question people have been asking since time immemorial.
To the ancient and classical thinkers, the emotion was largely inseparable from the act, both of which had divine characteristics. All you have to do to see this is look at the various polytheistic pantheons. You are almost guaranteed to find a god or goddess of love and sex. In Ancient Egypt you had Hathor. In Greece and Rome, you had Aphrodite, Venus, Eros, and Cupid. And in Norse mythology, you had Freya. (Now it's important to note that this is by no means an exhaustive list, just the generally most recognizable names.)