To be fair,whatever it is, if MC stops making such a fuss about it she won't get found out or will be able to easly refute that she was that adult.
But it's one of those "I, a XX years old person, reincarnated all-knowledgeable about the world but for some reason my intelligence matches my current age divided by 3! So I'll avoid MLs and have a peaceful life by always getting involved with them and seducing them", so don't try to find to much logic in it, just enjoy cute grills/hot buoys.