What Does The Monster Mean By The Phrase I Will Be With You On Your Wedding Night?

In Chapter 20 of Mary Shelley’s Frankenstein. Victor sets about his work, creating a second female monster. After following Victor and Henry through mainland Europe and England, the monster comes near Victor's workshop in Scotland to see his mate. In a fit of anger and guilt, Victor destroys the half-finished creation in front of the monster and tells the monster he will not continue. The threat the monster makes is an ominous one:"I shall be with you on your wedding-night." The monster then disappears into the night.
Victor feels extreme guilt for the deaths of William, Justine, and Henry. He is scared that the monster will continue to kill people until he gets his final revenge on Victor since the monster threatened this revenge would take place on Victor's wedding night. Victor believes that the monster intends to kill him, and he resigns himself to that fact. Feeling Elizabeth is safe from danger, Victor agrees to the wedding. But later in the novel, the moster fulfills his real attempt. While Victor is prowling the halls of the inn where the couple was living, the monster makes good on his threat to Victor, enters their bedroom, and strangles Elizabeth. Victor shoots at the monster when he flees, but the monster gets away without being wounded.