If you're looking for books that capture the same bittersweet, poetic vibe as 'I Love You, I Love You, I Love You,' you might wanna check out 'The Fault in Our Stars' by John Green. It's got that mix of raw emotion and existential musings, wrapped in a love story that hits deep. Another one I adored is 'Norwegian Wood' by Haruki Murakami—it’s melancholic and introspective, with a similar focus on love and loss.
For something a bit more surreal but equally heartfelt, 'Kafka on the Shore' also by Murakami could work. It’s not purely a romance, but the way it explores longing and human connection feels kindred in spirit. And if you’re open to manga, '5 Centimeters per Second' by Makoto Shinkai is a gorgeous, achingly slow burn about distance and unspoken feelings.