When I try to explain poly to my non-poly friends, I try to always stress that at the end of they day, our relationships are not that dissimilar. This is sort of different from when I try to explain queer relationships to my non-queer friends, then it's that one specific difference which is the sex we have. Now-hubby and I once got into an argument about Pride and why it has to be so (his words) "sexualized." It's because that's really the one difference between queer relationships and hetero ones, and it's the one time of year where we get to put that sexuality out on display and not be completely afraid for our lives because of it. If you think about not even being comfortable with holding your significant other's hand in public...you'd go a little overboard if you had an opportunity to actually express your love publicly.
But when it comes to my relationship being poly, I never feel that it's that outside the bounds of how other people formulate their relationships. The sex I have in my poly relationships is still sex.
In my own experience, it's easier for people to wrap their heads around, "Oh, so you have sex with more than one person, sometimes at the same time," than it is for, "Oh, you have 1:1 sex with people who have the same genitals as you do." I'm unsure as to why this is, but I have a feeling it has something to do with sexual orientation in general, and to get really deep thought mode on ya'll, with the way people perceive their existence.
So if somebody isn't attracted to people of the same sex, then it's difficult for them to imagine a life where they would be. I'm not saying it's impossible to empathize, I'm just saying for them personally that's not the way their world works. The perspective is different. I mean, maybe an otherwise monogamous couple will want to get "freaky" and try some light bondage or even like a threesome or something.
So when I bring up the type of things I do, it's not entirely outside their imagination to deal with.
But exclusively dating and/or being with somebody of the same sex for more than one evening? A bit more elusive for otherwise monogamous straight people, as far as I've found.
In any case, poly relationships being like other relationships. Think of all the things that are awesome in your monogamous relationship. All of those things are awesome in my poly relationship. Going on dates, cuddling, laughing, just sitting on your computers on a Wed night appreciating each others company (d'aww), etc. It's the same for things that are not so great sometimes in relationships, too. I feel like these don't get talked about as much, which is unfortunate. It's sort of like you're in this alternative relationship model and you can't admit that something is wrong because then it just adds fuel to the fire of everybody who was telling you already that you're relationship wasn't going to work. Honest question: do monogamous couples deal with this? I mean, outside of those relationships where for whatever reason the people around you don't like the person that you're with. Are there people who fundamentally say, "formatting your relationship in a monogamous fashion is wrong," and then as soon as you have even the smallest fight are all, "see? I told you not to do this and you didn't listen to me and now your relationship is failing."
Those things that are not so awesome in your monogamous relationship? Bickering about housework, feeling like you don't have enough time for each other, saying the exact same words as the other person but meaning something different and then your feelings get hurt. All of those things happen in poly, too. It gets complicated with multiple people dealing with the bad as well as the good. When things are good, they're good. When things are bad, there's additional involvement with the additional people (and opinions) in the relationship.