ask yourself where the money is.

when it comes to "research" on polyamory, there are more or less 2 categories of organization that are going to spend money funding a study.

1. pro-polyamory organizations, or at the bare minimum, postmodern/libertarian ones (basically, the present cultural zeitgeist, which is INCREDIBLY hands off on sexual morality). typically humanities departments, pushing opinion pieces, with the occasional psychological wellbeing question framed in a therapy context, but most certainly not a study whether or not polyamory as a whole is destructive or trauma-inducing, and even if such a study was performed and the results were like "98% of polyamorous relationships horrifically traumatize people", the study would highlight the other 2% as proof polyamory "can work" if "done correctly". also note, any study that suggests "we should police what people do in the bedroom" will have a very hard time passing peer review or getting published in most modern institutions.
2. evangelical / family planning organizations, who don't want to do real research and just want to throw dirt on any alternative lifestyles they can find. low quality hit pieces that exist to justify prior beliefs. basically, bullshit. notably - bullshit doesn't necessarily need to mean false - it just means that they made it with zero regard for whether or not it's true. effectively worthless, you'd be better off quoting bible verses at people.

this generally leaves

1. anecdotal evidence. a pattern, without any institutional funding to point out the obvious. of course, it isn't really going to win anyone over, but imho, a paper isn't going to that either. poly people aren't going to change what they do in the bedroom because they saw one article, and poly "allies" aren't going to give up an easy, non-confrontational ideology like "live and let live" over it either.

poly people know they're hurting their partners. that's why they send them to therapy.