He pretended not to hear and she pretended that he was asleep. She wanted all of his love. It is a reasonable claim to make for lovers.
But, one part of his heart has always been on Katarina. The connection between him and Katarina is of magical nature. It is unlike the feeling he felt for Sofia.
Sofia….is a person who he had known. Someone he had known out of familiarity. His first love that he could not realize when he was in high school
There is a sense of nostalgia, and a connection between him and those past moments. Their meeting was a series of coincidences that piled up and become fate.
Familiarity that breeds affection. Affection that birthed love. And before long, naturally he fell in love with her, even without meaning to
Loneliness. Familiarity. Affection. All of these affect his feeling toward her until it is what it is today.
Katarina on the other hand, is like those encounters in some romantic stories.