lui elle

Question

Why is "le proffeseur n'aime que lui" wrong (correct: elle) when "Pauline n'aime que lui" is a correct example?

Accepted Answer

Hi Tine, 
It depends on what you are trying to say:
Le professeur n'aime que lui = The teacher only likes him
Le professeur n'aime qu'elle = The teacher only likes her
Le professeur n'aime que toi = The teacher only likes you
etc.
Here you use what we call stress pronouns and below is the Kwiziq lesson explaining more on this subject -
https://french.kwiziq.com/revision/grammar/moi-toi-lui-elle-me-you-him-her-simple-cases-that-use-stressed-pronouns
Hope this helps!