Mine, Ours and Not Mine.

Mine...

I am a firm believer in personal responsibility. By this I mean at each person is responsible for themselves... their thoughts, feelings, behaviors, and reactions are their own individual responsibility.  We are each responsible for the choices we make and the actions we take, and we are responsible for the repercussions of those actions.  I am responsible for my own health and well being and making sure that my needs are being addressed, I am responsible for my own emotional state and how I respond to it.  

By the same thread each of you are responsible for your own health and well being and making sure that your needs are being addressed, etc.

Ours...

In some relationships we develop shared responsibilities, by mutual agreement.  Our responsibilities include the time and effort to maintain that relationship, following through on any commitments within that relationship, and clear and honest communication within the relationship.  Shared responsibilities could include other things like co-parenting, shared property, or joint debts (though I am solo poly and currently my life does not include any of these things).

Not Mine...

What I am not responsible for are other people's actions and choices nor the repercussions of those things on their lives.  

I've come to a point in my life where I am simply unwilling to be thrust into the middle of someone else's mess, and so I find myself saying repeatedly "that has nothing to do with me".  

Don't get me wrong, I truly understand that meaningful relationships benefit greatly from sympathy and empathy. Being understanding and supportive of someone when they are struggling with the things that are happening in their lives is not the same thing as allowing them to place responsibility for their difficulties on me.  I put a lot of time and energy into the relationships I have with the people that are important in my life. I listen and when asked provide suggestions or my perspective on the situation. I even volunteer to help with things that are within my ability (and availability).  But I don't take on anyone else's troubles as my responsibility to solve.

I think it is especially important in polyamorous relationships to be aware of our personal responsibilities and to be honest about how our personal choices lead to the situations we find ourselves in.  It's easy to fall into faulty logic and play into a post hoc ergo propter hoc assumption, whereby someone will claim that these things happened after this poly relationship started therefore all of the things are caused by the poly relationship. It's completely ridiculous to think that polyamory is the cause of every issue in a polyamorous persons life. That would be like blaming my cats because I need to work for a living (if they had only been trained monkeys they could earn money to support me in the manner to which I would like to become accustomed). Similarly, it is illogical to claim my doctor is responsible for my sprained ankle (if they had only mutated my genes the way I wanted them to I would have a super healing factor like Wolverine).  
Still, I've seen this happen to a lot of people, there are difficulties to deal with and somehow they decide that everything is due to their partners (or one of their partners' other relationships), as though house work, finances and child rearing wouldn't be a problem if only that relationship worked the way I want it to or this other relationship didn't exist.  

If my partners weren't poly then I wouldn't ever have to do housework, seriously?  My dislike of dusting and scrubbing floors stems from ancient personal dislike and doesn't have anything to do with any of my poly partners.

Difficulty dealing with ones teenage child stem directly from choosing to be a parent, they are not the responsibility of someone who is not parenting that child

If I don't feel like I'm getting enough time and attention from my partners, that is something that needs to be addressed by my partners and not to be blamed on people outside our relationships.

When I am unhappy, feeling strained or even dealing with the specter of jealousy, it is up to me to be reasonable enough to figure out what is going on with me and what is actually contributing to my issues.  I have to pull out the strands of what is happening and where it came from, I can't just wad everything up into a ball and toss it into someone else's basket.  I don't just decide that everything has gone horribly wrong because of my relationship style, or push off responsibility for the results of my actions and choices to some third party.  I make my choices and I deal with the consequences. I expect everyone else in my life to do the same, because I won't take your stuff on for you and I'm not afraid to tell you "that has nothing to do with me".