I’m also from the US, actually! :) As for your question about cheating, I really think it depends on the people involved: as long as there is healthy, open communication with all involved, I don’t see why you can’t have multiple styles of relationship at the same time — provided that everyone is in agreement that such is okay. That’s why, in poly circles, there’s the term “consensual non-monogamy” (or even “ethical non-monogamy”), and the “consensual” part is important: non-monogamy without mutual, informed consent is cheating. But non-monogamy with mutual, informed consent is ethical. At least that’s how I understand it.