I feel like Kai stopped writing 'Love' partly because he blames his problems on Daisy and that he's kinda mad at Daisy at the same time and he just doesn't want to write the word 'love'. He's confused and he's angry and broken and I feel like 'from' represents / symbolizes his sad, depressed mind state. There simply isn't anything to 'love' anymore in his life. They're all just rants and letters now which don't really have anything about love.