It might be best for the girl to quit this job. She's getting too jaded already. She's dangerously close to a point where the customers won't anymore feel like they are getting what they paid for. In fact I reckon many a customer would notice already.
Rental imouto--> Becoming closer---> Love--> Girl dies---> Guy Somehow returns to the past with intact memories and a phone--> weeping for a bit then Re:Zero all the way