Non-monogamy is an inherently challenging relationship style, and not just because of the things many on the outside imagine, such as jealousy and time management. Those are indeed challenging things, but I've discovered that what turns out to be even more complicated are all the interconnected relationships between all the parties involved.
It's no longer A&B sorting out their relationship, but if they're involved with C&D, we have A&B, A&C, A&D, B&C, B&D, C&D, plus all the ABC etc. combinations. Even if some of those people in those relationships haven't met each other or don't have personal communication, they all affect each other in direct and indirect ways.
When everything is going well, it's fun and exciting to explore the new people your partner(s) have brought into your life. There can be much giddiness in discovering all the awesome things about them that your partner(s) like/love. You may find yourself liking and/or loving those things too, metamours (your partner's loves) turn into paramours (your loves), and you may settle into some polyam smugness about how great you are all are at this non-monogamy thing.
It's when things aren't going so well that it all gets extra extra complicated. If your partner and their paramour are fighting, where does your loyalty lie, especially if that paramour is also your paramour or close friend as well? You don't ever have to take sides in anyone else's drama, but it can be nearly impossible to stay completely neutral when people you care about are in conflict and distress. As much as we feel joy when someone we love is receiving love, it's easy to feel extra mama-bear rage when someone hurts them and it's difficult to give the person who has done the hurting a fair hearing.
My husband Flick and I consciously do our best never to talk shit about the people we're involved with together (or really ever, but we are human) but it can be incredibly hard not to talk about things someone may have done that hurt, angered, or upset us. It's also incredibly challenging not to break confidences of those we're involved with when we need to talk about the difficulties we might be having in one of our relationships. We all need to have sounding boards we can depend on, but the more overlap there is in the relationship Venn Diagrams, the harder and harder it can be to have or be a neutral ear.
If your partner and their paramour have done something that feels like a betrayal of trust in your relationship, it's very difficult not to put most of the blame on the person you're less invested in. It's much easier to get angry at someone you don't know as well, rather than directing your anger at your nesting partner, who is often equally responsible for the breach. Just as ‘the mistress' is almost always the enemy in most infidelity stories, anger at betrayals of varying sizes tend to skew toward the person you know and love less.
Another potential minefield is if a metamour wants a closer relationship than you're up for (or vice versa) and it can be difficult for all involved if one person is seen to be difficult and reluctant to engage. Sometimes your partners might also want you to have a closer relationship than you necessarily want with a metamour and it can be really awkward to need to explain that while they're great, you don't want more from that connection than what you have. Wanting to please both your partner and metamour can lead you into diving deeper into something than you might be up for. If that relationship doesn't work out, the fallout can be much larger than if you'd kept the boundaries firm initially.
I've learned the hard way how essential it is for me to maintain my boundaries and take things at my own pace. I move more slowly than others when it comes to forming love bonds but I know from experience that when I try to rush to meet someone else's speed, it doesn't end well for anyone. We also don't have to love everyone our partner(s) love. Sometimes we simply won't be a good match and that's okay.
As I write all this out it can be easy to wonder why the hell we do any of the polyamory stuff when there are so many ways for it to complicate our lives. I can say very honestly that there are days when I'd like to hit the rewind button and go back to casual sex only, but then I think about the incredible people that are embedded in my daily life and wouldn't want to be without them.
It is indeed complicated but the things worth having in our lives often are.