I think a lot of religions are heavily obsessed with "thou shall nots" and "thou shalls." I think rules are a hard way to deal with religion. (But it is easier with clear cut rules.)
As an example, the Old Testament preached that it was good morality to kill a woman in front of her parents if she was a non-virgin bride. There is no way we can see that is good today. The Old Testament also said that woman must marry her rapist if she was not already married or engaged. There is no way we can see these as good things, though the Old Testament claims that these are some of God's perfect and eternal laws.
I think a much better route is to go more with the New Testamrnt style of teaching. Throw away the old rules and just keep two: Love God and love your neighbor. I think if you base your morality and beliefs upon this idea, then life becomes simpler and also more complex. (I am an atheist, so take what I say with a grain of salt.)
Long distance relationships are hard. I know it heavily pushes a monogamous relationship. In theory, if both people are poly, then there is no need to break up. Even if they find someone else, there is no reason to end the other relationship (unless the new person insists on monogamy.)