In Frankenstein, what are the similarities and differences between Victor's desire for a mate and the creature's desire for a mate?
There are far more differences one can find between Victor and the creature's desire for a mate in Mary Shelley's Frankenstein. The similarities and differences speak to the themes of alienation/loneliness, nature verses nurture, and the quest for Forbidden Knowledge.
Victor has a potential "mate," Elizabeth. In the beginning, he alienates her to feed his obsession to reanimate life. He spends years away from the woman who loves him more than anything in life.
Later, Victor is questioned by both his father and Elizabeth if he is in love with another (given he has yet to fulfill his family's wish to marry Elizabeth). Victor replies that he loves only Elizabeth and will marry her upon his return to Geneva.
Unfortunately, prior to his return, he is warned by the monster that he (the monster) will be with him on his wedding night. Victor, although worried, marries Elizabeth (only to have her murdered by the monster).
The monster has no one. In order for him to find happiness, he believes that he must have a mate. He asks Victor to create a mate for him (given he believes a monster like him will be the only one who will love him). The monster agrees to leave all of mankind with his mate.
Victor agrees, only to destroy the monster later (right in front of the monster). The monster, as stated before, finds Victor on his wedding night and murders Elizabeth.
There is really only one similarity between both Victor and the monster when it comes to their "mates": both die. Each is left alone, only seeking to destroy the other for taking the one thing which meant the most to them.
Victor has a woman who loves him, but he alienates her.
The creature has no mate, and desires one more than anything.
Elizabeth is a natural human being.
The monster's mate is (was to be) another abomination against God.
Elizabeth loved Victor.
There was no promise that the new monster would love the original.