Brillyant said "Hollywood is responsible for some huge chunk of the sum total of all relationship problems."

To my way of thinking, that seems to pretty clearly be asserting a causal relation.

Hollywood's role here is promoting and popularizing a set of existing relationship tropes, not necessarily coming up with those tropes in the first place, and it isn't the sole champion of these tropes. If an unspoken or explicit agreement took over the majority of Hollywood studios, script writers, and so forth, then we could get a healthier, more realistic set of relationship tropes promoted and popularized, competing with the unhealthy relationship tropes.

What would happen? People's expectations would be more in line with reality, since the media they consume that shapes their expectations is more in line with reality. They would be more inclined to communicate with each other because they are inundated with examples of people communicating with each other freely to resolve isues. Average relationship health would increase.

The unhealthy tropes would still exist. They're popular now for some reason, and that reason probably wouldn't simply disappear, plus they've got a lot of inertia, in terms of both existing media and existing mindshare. And if the magical collusion for healthy relationship tropes were merely between Hollywood organizations, then advertising agencies and novellists and songwriters and other media producers would still be able to promote the unhealthy tropes. But removing a major source of reinforcement of the problematic ideas and replacing them with a source of reinforcement of less problematic ideas would result in fewer problems overall.

Again, this is expounding on Brillyant's point, not offering evidence. I want you to have a clear idea of one of the better forms of that position, but I don't have the data myself. It should be relatively easy to find evidence for similar issues, specifically eating disorders, but also violence and violence-accepting attitudes toward women.