Dopamine, testosterone, and estrogen are associated with novelty and can lead to an enhanced enjoyment of another person's scent.

“Some people when they are in a new relationship because dopamine and the hormones, testosterone and estrogen are associated with novelty and the sorts of behaviors that often are associated with new relationships those three molecules; dopamine, testosterone, and estrogen kind of work together. And oftentimes people will say or report when they're newly in love or in a new relationship that they're just obsessed with, or they just so enjoy the scent of another person so much so that they like to borrow the other person's clothing or they'll sniff the other person's clothing or they can even just in the absence of the person they can imagine their smell and feel a biological response, something that we'll talk more about.”