Based on some analysis, one interpretation of the portrait is that Miss Piggy died giving birth, and this was a post-death portrait.
Over Miss Piggy's head there is no candle, and yet a lit one over Kermit. If this was a marriage, her hair would be down, however her hair is up, indicating she is already married, as unmarried pig women wore their hair down. In the back, on the mirror frame, there's little paintings from the life of christ, and Miss Piggy's reflection is shown on the side of the mirror lined with paintings of Jesus's death and resurrection. To add to this, they're shown in winter clothing, however outside it's clearly spring or summer. There's even a figure carved on the bedpost, of a saint that was supposed to promote childbirth/cure infertility.
Basically Miss Piggy's fucking dead.