Dark Knight: The Second Chapter (2) - S1-E3
Continuity mistake: The blood stains on Nick's white turtleneck are lighter, then darker, then lighter again, and migrate to different positions, both during his fight with LaCroix in the abattoir, and throughout the hospital scenes afterward. (00:10:15 - 00:19:30)
Answer: Nick was sick and tired of being an immortal bloodsucker. He wanted to be human, fall in love, get married, have children, grow old and die. As for Janette, according to her, she fell in love and the passion she felt "cured" her of her blood lust.