(Note, this is a Roman fairy tale, therefore I will use Roman names. Cupid is Eros, Proserpina is Persephone, and Venus is Aphrodite)
Psyche was so beautiful that her mother foolishly bragged that she was more beautiful than Venus. This naturally made Venus angry, so she commanded Cupid to make Psyche fall madly in love with something gruesome. Cupid, seeing Psyche, was so stunned by her beauty that he accidentally pricked himself and fell madly in love with her.
Eventually a plague fell about the kingdom, and the king and queen were commanded to leave Psyche out on a mountain for a beast to eat. Cupid took Psyche, though, and they lived happily in a beautiful castle. The only problem was, Psyche’s sister’s were jealous.
So, when the sisters found that Psyche had never seen Cupid, they told her that she should see him, because he must be a monster. Psyche did so, and while leaning over, spilled a bit of hot wax on Cupid which made him vanish away.
Psyche, grief-stricken, went to Venus to beg to be reunited with her husband. Venus agreed that if she completed three tasks she could be reunited with her husband.
The first was to sort a huge pile of grain into piles, which she did with the help of ants.
The second was to gather water from the river Styx (which will kill a human to touch).
The third, and naturally most difficult, was to collect beauty in a box for Venus from Proserpina. According to Venus she was wearied with healing Cupid, and needed the beauty.
Psyche fetched it, but then became curious, and wondered if she could borrow a bit to become more beautiful for Cupid. When she opened it she fell down as if dead.
Luckily she was brought back to life, deified, and stayed with Cupid forever.