>>192032684>Eren and Historia never show any romantic feelings
I agree, but they showed a strong friendship and care for each other. They both refused to sacrifice the other in order to save the world. That is already a great foundation. You can built a romantic relationship from there.>the wish to make a child
Eren is the second son of a man who lost everything and was trying to do it right this time and failed again. Historia is the daughter of a woman who couldn't lover her.
Yes, it was never implied they wanted children, but if the theme is to not repeat history and to surpass your parents, it makes sense for them to end up with a child.
Especially for Historia, who can finally show love to her child instead of pushing it away. It's a great way to conclude her story.