Happy to be labelled stupid. But yeh. Dunno what pills you’re taking.
Your grasp of the basic definitions of parasitism and mutualism is great 👍, but it seems you’re refusing to acknowledge the complexities and nuances of biological relationships.
These are not static, black-and-white definitions. Nature isn’t a simple dichotomy of “mutualism here, parasitism there”. It’s a continuum of interactions that evolve and change with conditions.
Consider the cleaner fish as an example. It’s an illustration of facultative mutualism. The fish provides a service by removing parasites from a host fish—a clear case of mutualism. But what happens when the cleaner fish starts taking bites of the host’s flesh, causing harm? Suddenly, this mutualistic interaction turns parasitic.