The Tenacity of a Man and Woman wanting to have a family is an all-powerful thing, one that can't be stopped by anything as mere as Logic! Especially in manga! They will have seggs, they will have children, and they will live a happy life together!They can never have a family.
Probably read “Boku no Kanojo wa Dekkawaii”What should we do now?😥
The ideal ending would have been her gaining the ability to turn giant or normal-sized at willI would have preferred an ending where the giant size was fully embraced rather than handwaved as the result of another "unfulfilled wish"
Perhaps he needs to learn to do cave exploration.Yumeji should take scuba diving lessons