I found an article titled The Heart of the Matter: Eros and Agápe that says:
Finally, a few words about the goddess Agape. She is virtually ignored by Plato and Aristotle, as well as every other Greek philosopher, so all we know about her in the specifically Greek context is her mythology. As I noted a moment ago, she is the goddess of divine love. She is also Aphrodite’s sister. Agape was idolized by all the women in ancient Greece because she refused to give in to any man’s orders. Perhaps she was the first feminist? Greek women never saw themselves as very important, even in marriages. This wasn’t so for Agape. She knew that men felt superior to women but she saw no evidence of their alleged supremacy. She vowed to be an independent goddess and to never let any man or god lie to her. As years went by Agape became lonely, but discovered that she had stopped aging and became increasingly sensuous and beautiful. The gods took notice and tried to seduce her, but they only made fools of themselves in the process. Mortal women began to realize that men weren’t the only power in the universe, and that women could make decisions of their own. Greek women began to achieve a higher marital status and were treated more fairly. This only made Greek men more attracted to them and less likely to break their marital vows. One wonders why Greek philosophers – all men – have so little to say about her?
No source is cited for this myth. What evidence, if any, is there that Ἀγάπη was a goddess and not just an abstract word for love?