Partner is new to poly & he sometimes fuck up, like everybody does & can do in poly. He & his other partner are Mono(she)-poly(he) relationship. My partner isn’t all that great at the full on communication & check-in thing but we are working on it & finding solutions. However my metamour isn’t really getting that communication can still go wrong. Both of their communication is unhealthy sometimes & I find myself to pick-up the pieces afterward. We talked about it but what else can I do about it?

Give yourself permission to stop doing that cleanup work after he makes mistakes. It is not your obligation or responsibility to manage your partner’s behavior, or his metamour’s feelings. Decide what is a healthy boundary for you to set and set it, gently but firmly.

For me, personally, I have a policy where I can hear and receive and empathize with my partners when they have an issue with another partner, but I do not give advice or share my own perspective. This can be hard and frustrating when they want to ask “what should I do?” or “do you think they’re being unfair?” but I hold to it, because I’ve found that it just gets too messy otherwise. I’m not saying this is a good rule of thumb for anyone but me, just giving an example. 

If you’ve seen a pattern that is starting to bother you, speak up - but stay focused on you and your partner’s relationship. “When you’re having a fight with Blargaret, you get snippy and withdrawn around me, and then I feel like I have to facilitate you two making up so I can get you back. I’m no longer going to take on the emotional work of resolving a situation that I didn’t create and have no control over. Let’s talk about how we can solve this, together.”

It is great that people who are newly polyamorous often have experienced polyamorous partners to ‘guide’ them, but be mindful of how much emotional labor you’re doing on his behalf. If you’re the training wheels, you gotta let him do the pedaling. And if, ultimately, it becomes unhealthy or untenable for you to keep dating someone with a tough metamour situation, it’s okay to end the relationship.