Normally I would agree with you, but in this case, he rejuvenated AND lost his memory. He fell in love with someone who was his age in his mind. I believe his mental age was also affected with the memory loss, as his only memory was from when he was that age. And then, after he got his memory back, the first thing he did was tell the one he fell in love with about his actual age, and she was fine with it. Getting his memory back did not remove the feelings that were created while he didn't have his memory. It was also his first love. Even more of a reason to not just forget about it. He thought that his love would not still love him with his actual age, so he knew it was weird too; but he still told her first, in order to give her the choice. If he hid it, I would have had a much bigger issue.
Once this started showing romance i was just grossed out. it has never been my thing when the main couple have a large age gap. Like the mc is 90+ y/o and his lover is 20 something. Just no, like eww no that is gross.
liked this in the beginning but am dropping this now.