It would be funny for a side scene if Meloetta asks the MC to take her clothes shopping and lets him help her choose the new clothes but they end up making a big mess in the changing room for obvious reasons.
Another version of this could be that Meloetta does not have any pregnant clothing for her later so she asks the MC to come with her to see the tailors that have been making her dresses while she was an idol. The problem is the tailors only know of regular pregnant size and not the MC's dozen of kids at once size so the MC has fun with her to give the tailors a good example to go off of. Plus the tailors are fans of Meloetta.