I had a feeling he was also the one behind her regression as he was way too familiar with her. This is honestly the better case scenario of amnesia you could get with stories like this. Would it also be nice she has also known him in their youth? Yes, but the demon could have made the price so much worse. He did the man a favor by only taking away ger memory of him. Although her head exploding because of her remembering him is a bit much.

Please, tell me I'm not the only one who thinks Diana not remembering Laurie is just a small issue / price to pay for her to be able to redo her life and live... ( ̄へ ̄)
Is it tough? Sure, but it's not like you can't create new memories and bond. Maybe it's even better as Diana can see Laurie as a man from the beginning and not just some cute orphan she helped... Idk man, the devil could make the contract so much worse when it comes to repercussions that this seems rather minor... ┑( ̄Д  ̄)┍