In the Lovers list she is referred to as Emily Pepper, probably because she kept her name for professional reasons as it is mentioned that she is a realtor. Nowhere within the game does anyone refer to her as Emily Harrington, even the MC only refers to her by her first name.
Potentially a bug then. Did you change Roger's last name in your play through. The code is supposed to copy whatever last name you gave to Roger over to Emily and then rip the first letter and assign it to....someone whose last name is not defined.
The hard coded default though is Harrington. I have no idea where Pepper is coming from....?
edit:
Yeah, just double checked. Emily's last name should reflect whatever last name you gave the MC. So if you changed the MC's last name in your game, Emily's will also change.
Let me know if you didn't change the last name to Pepper because then there is a strange bug somewhere. Because no in my game has the name Pepper.