Venus was very jealous of Psyche because they were worshipping her over herself. It makes sense for her to be jealous because is the goddess of love and beauty and the mortals thought psyche was more beautiful than her. It's just like saying that Venus is the goddess of love now and not beauty because we find one better.
I think there is a moral to this story. It is basically saying that you should trust your partner in life because good things are bound to come. In Psyches case it was to not look at her husband but of course she wants to, they are married! For Psyche, it worked out at the end because she became a goddess and ruled next to Cupid.