I think I grouped my ideas poorly; the two kinds of bias you point out would be better descriptions of the two topics I'm thinking of writing about. (And they definitely seem to be separate enough that I shouldn't be writing about them in the same post.) So, to clarify, then:
Topic 1: Individuals in industrialized cultures (but the U.S. more strongly than most, due to religious influence) very rarely question the default relationship style of monogamy in the absence of awareness of other options, and usually not even then. This is less of a bias and more of a blind spot: there are very few people who are aware that there are alternatives to visible monogamy. Non-consensual non-monogamy (cheating) is, of course, something of a special case. I'm not sure if there's an explicit "unquestioned assumptions that rule large aspects of your life" category on LW, but that kind of material seems to be well-received. I'd argue that there's at least as much reason to question the idea that "being monogamous is good" as the idea that "being religious is good." Of course my conclusions are a little different, in that one's choice of relationship style is ultimately a utilitarian consideration, whereas religion is nonsense.
Topic 2: Humans have a neurological bias in favor of (certain patterns of behavior associated with) monogamy. This would include romantic jealousy, as mentioned. While the research in humans is not yet definitive, there's substantial evidence that the hormone vasopressin, which is released into the brain during sexual activity, is associated with pair-bonding and male-male aggression. In prairie voles, vasopressin production seems to be the sole factor in whether or not they mate for life. Romantic/sexual jealousy is a cultural universal in humans, and has no known purpose other than to enforce monogamous behavior. So there are definitely biological factors that affect one's reasoning about relationship styles; it should be obvious that if some people prefer to ignore those biological factors, they see some benefit in doing so. I can say authoritatively that polyamory makes me happier than monogamy does, and I am not so self-absorbed as to think myself alone in this. Again, this is a case where at least some people can become happier by debiasing.
And that still leaves Topic 3: jealousy management, which I imagine would look something like the sequence on luminosity or posts on akrasia (my personal nemesis).
Thanks for your comment; it's really helped me clarify my organizational approach.
Several of us have enough trouble forming and maintaining even a single romantic relationship. :(
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