In Gakuen Alice, Yuka Azumi stole Narumi's Alice when she was running away. Consequently, he lost all ability to love her or anyone else. How does this work?
When Narumi used his pheromones to make her love him. That made her lose control of her Alice, which had the result that not only Narumi's Alice was stolen, but his love-feelings, too. It seems that the Pheromone-Alice is connected to the emotions, and an out-of-control-stealing-Alice steals more than it's supposed to. If Yuka had retained control, Narumi would still have his ability to love.