It's up to interpretation. Spoilers ahead.
Everything below is more or less my opinion and interpretation of the story after reading both the manga and novel:
In both the novel and manga, the author has shown us that the characters are just humans and therefore unreliable narrators / source of information. The aftermath of the story is narrated by a present Sanagi who believes she will die, but her internal monologue is repeatedly interrupted by Kousaka, who lets her rely on him and let her tears out. Given this, I don't think we should necessarily conclude that she dies after the story ends.
Something else that I think supports this is both the title and interactions within the story.
Initially when reading "Parasites in Love" you assume the title is metaphorical and refers to the two main characters relying on each other to grow as people, but by the end we know it refers to the actual parasites in their brains. Or do we? I honestly think that the title can refer to both and that it's not actually mutually exclusive:
"Sanagi painted the colours Kousaka left unpainted, and Kousaka painted the colours Sanagi left unpainted, completing each other's worlds. By doing this, the world stood out more clearly."
By the end their love is proven to be genuine and mutual, so although Sanagi doesn't have her parasite to rely on, she has Kousaka, and Kousaka has her. Hence, "Parasites in Love", both literally and metaphorically.
TL:DR
I don't think Sanagi is a reliable narrator + the author has left a red herring (or two, really). The conclusion can be interpreted as a happy, yet difficult ending when given much thought.
- Melina1 year ago1

For some reason it's not letting me spoiler mark the entirety of my message, so I left a manual warning
Oh well!
- AnimeBound1 year ago1

Umm I think it's a happy ending after all since I didn't find anything extra on the novel. But still the ending kinda made my heart ache. She was happy and sad at the same time ig.
- AnimeBound1 year ago

Umm I think it's a happy ending after all since I didn't find anything extra on the novel. But still the ending kinda made my heart ache. She was happy and sad at the same time ig.
- AnimeBound1 year ago

Umm I think it's a happy ending after all since I didn't find anything extra on the novel. But still the ending kinda made my heart ache. She was happy and sad at the same time ig.
