well this is very messed up, apparently the MC protected her from the dragon and lost the memories about her, and to “compensate” for his sacrifice, he was “sold” by his father to marry her, but as he had no memories about her and thought she was against it too (and thanks to the poorly finished phrase she used right after they left her fathers office made it clearer at least to him) he decided to pay for the “fathers debt” by working for the family of the girl. So father and daughter decide to treat him as an employee with the intention that the two can create a new bond... so if someone else pays for his debt that person becomes the “his new owner” because what FMC is doing is no different from buying a dog and not wanting anyone else to pet him, and still making sure of reminding him about “his debt” time by time