I've thought Saten and Uiharu in "A Certain Scientific Railgun" seemed like an old married couple as well. Especially in the "Silent Party" arc, when Febrie was staying with Uiharu, and Saten was staying in Uiharu's room to help. The scene when they were sitting around the table having dinner looked just like a young couple with their newly-adopted daughter.
I've thought Saten and Uiharu in "A Certain Scientific Railgun" seemed like an old married couple as well. Especially in the "Silent Party" arc, when Febrie was staying with Uiharu, and Saten was staying in Uiharu's room to help. The scene when they were sitting around the table having dinner looked just like a young couple with their newly-adopted daughter.