Love is probably a major theme. It might be about the different forms of love, like romantic love or love between friends or family.
Loss could also be a theme. Maybe the characters lose someone or something important to them, and this loss affects their hearts, which is where the title 'half of my heart' might come into play. It could be a physical loss or an emotional one, such as the loss of a relationship or a dream.
One possible theme could be self - loathing. Since the title says 'my heart hates me', it might be about a character who has a strong negative feeling towards themselves.
Love could be a possible theme. If someone's heart is being 'rocked', it might be due to a new or intense romantic experience.
One possible theme could be creativity. Since it involves 'design', it might explore the creative process of coming up with something related to a heart. Another theme could be love, as the heart is often associated with love. Maybe the design is of a love - related object or place.
One possible theme could be survival. Just like in Half - Life 2, the dog would have to face numerous threats and find ways to stay alive in a harsh environment.
One possible theme could be self - acceptance. If the girl has some sort of disfigurement or difference on half of her face, the story might be about her coming to terms with how she looks.
One possible theme could be time management. Since it's focused on a day and a half, it might show how people make the most of a short period of time.
One possible theme could be survival. If it's about someone being in a difficult situation for a day and a half, like being lost in the wilderness, survival would be a major theme.
Another theme could be self - discovery. In a short period like a day and a half, a person might learn something new about themselves. For example, they could face a challenge during that time and realize their own strength or weakness.
One possible theme could be confusion. Since it's not a fully - defined relationship, there would be a lot of uncertainty about where the relationship is going.
One possible theme could be decay. Given the reference to 'half - life', which is often associated with the decay of substances in science, the story might explore how things break down or deteriorate over time, whether it's physical objects, relationships, or ideals.