Quote 1
The fair girl went on her knees, and bent over me, fairly gloating. There was a deliberate voluptuousness which was both thrilling and repulsive, and as she arched her neck she actually licked her lips like an animal, till I could see in the moonlight the moisture shining on the scarlet lips and on the red tongue as it lapped the white sharp teeth. (3.32)
The vampire's kiss is described in very sexual terms. And the traditional power dynamic is reversed—the woman is the sexual aggressor, and Jonathan is the passive one.
Quote 2
She still advanced, however, and with a languorous, voluptuous grace, said:—
"Come to me Arthur. Leave these others and come to me. My arms are hungry for you. Come, and we can rest together. Come, my husband, come!" (16.20-21)
Again, vampire Lucy is too sexually aggressive. In the world of Victorian England, that sexuality needs to be repressed!
Quote 3
A woman ought to tell her husband everything—don't you think so, dear? (5.6)
Lucy and Mina like to exchange ideas about all kinds of things, especially (since they're both engaged) the roles of husbands and wives.