Mom is no longer a fighter, although she continues to train and get stronger. The problem is that sometimes she is too overprotective of her son (and husband) and due to her power and size she can be quite intimidating for some girls. For that reason, the protagonist tries to convince her to give her time to prepare the girls so that her mother does not end up sending them to the nearest hospital due to an accident as she says in the game. (Since Mama would not be calm if she did not test them as well and he knows very well how strong her mother is.) Although I assure you that sooner or later they will end up meeting her again.
By the way, the girls become stronger by leveling up in the game (What they do not do is get bigger by training). However, I want to create a mechanic where you can make the girls become even stronger through "special training" with the protagonist. And also create another mechanic where you can make the girls have "growth spurts" and you can make them even bigger and stronger. (Since the reason why Sena is so strong now is because of that "growth spurt" she had. She was never a very sporty girl... In fact Sena loves video games, manga, anime and delicious food. In another world, she would surely be chubby, but in this world those things don't happen to girls XD)