If you've got someone who, upon hearing about an issue that their partner has got, embraces that issue and makes it their own, that is high potential for drama, especially when you've got a near-unlimited supply of issues with a multiplicity of partners.
(For example, if I were to be prone to this, I would embrace my partner's co-worker issues and go around muttering that bigotry in the workplace ought not to be allowed, and I needed to go down there and have a few words and maybe start talking lawsuits because of faith-based discrimination in the workplace, as well as embracing my other partner's school issues and grumble about rude kids and crappy equipment...)
When you've got more than one partner and all of you share problems, then the drama level goes way, way up fast, whereas if you've only got one partner and you share their issues only, you've only got two people's worth of angst rattling around in the relationship without any brakes on.
However, if you're one of those people who can listen to someone vent for five minutes about a problem, and then soothingly mutter, "That sucks, dear," but remain emotionally uninvolved other than being concerned for your partner's welfare, then you're well-disposed to being in a multiple-party relationship, being not disposed to take on the angst of everyone who vents to you.
It's not just about the communication, I found, but how you handle the communication when you've got it.