One of my sims completed actor aspiration and celebrity aspiration too. He was ok with his 5 star level when he was single because I usually hang around all over town. But after the marriage, he suddenly got triple twins daughters and he had to be stuck at home for a week, then I got an alert his fame is fading away... So I think it's still decaying even though he completed both aspirations. If you want to live just as a normal citizen, then you can stop it in game option. Then your sim will be safe.