Here’s some early Dies Irae explaining how it got Venus from Star. Although doesn’t help much just how the union is fated doom.
The demon Lilith, the evil woman, is described as a beautiful woman, who transforms into a, butterfly-like demon, and it is associated with the power of seduction.
Star wields her wand which resembles the Star of Ishtar which is Ishtar's “MAGIC WAND" It actually says magic wand.
Istar Eshnunna, the Akkadian counterpart of Sumerian Inanna the goddess of fertility, love, war, sex, and power. She represents the planet Venus, 'unique star'. Reportedly, Inanna means Great Lady of An, god of heaven or, goddess of life.
The Hebrew word that referred to the morning star was translated into Latin as Lucifer. Morning Star which comes from Venus. (This is star)
Star wields her wand which resembles star of Ishtar, while Marco’s new wand resembles the spear and shield of Mars.
Both symbols represent the different sexes. The blood moon wasn't a sign of love, but a sign of tragedy of lovers vs lovers, and the end times. Otherwise known as Dies Irae. Basically their union like you said will cause issues.