His father could tell that Leoni fell at first sight for Reudiger. They weren't in love, but I guess his pride as a man hurt that his wife was looking at another man. I think there was also the factor of danger from the royal family, so mixed with jealousy it led him to take their son and disappear. He went to the North to work for some bastard who did inhuman experiments, but as they were not allowed to leave anymore and got into danger, he put a spell on their child to put him into a slumber at the cost of his life. The only way to wake him up was to use the blood of the caster. So the Northern bastard could do nothing do the child since the only person who could wake him up was dead. Reudiger found him after Leoni's disappearnce thinking the child would make her come back. When she learned of her childs situation she brought his father from the current timeline and used his blood to wake up their son. And in the future he got to see his mom through the painting, he visited her but had to be supported by magic(?) since he didn't exist in that timeline. In the end the baby had a happy ending (●'◡'●)ノ
Someone please tell me about the first son like how did he get lost that's so sad