Responses
Are u seriously asking or was it a joke? ε=ε=(ノ≧∇≦)ノ
Well, if I'm not wrong it was when they went to visit Takaba's omega father, and then they sat in a park? looking at Takaba's siblings playing together. At that time Keisuke told Takaba that he's sorry he can't give him children while touching his stomact and crying.
This is just a guess?
He probably can't give him any children because of all the medicine that he took before (not only the heat suppressant med but for pregnancy thingy?)

Now i get it why there's no baby for Takaba and Keisuke... ╥﹏╥