Phys - I have the same deal with worrying! It's been really useful for me to figure times when I'm making things more difficult by not trusting the net. Giving people space to process things... Being okay with the fact that this relationship adventure probably does have all sorts of influences in our moods, and is possible subconsciously triggering things (in part) at any time, but that it's sometimes impossible/impractical to vivisect which bits are "poly" issues and which aren't, and letting each person be responsible for their own communication. If my partner says it's not an issue, I trust that it's not. I will be open to hearing that they have changed their minds, but I will not second guess the situation. Trusting each other to bring things up when we feel we need to talk about it. Enjoying the fact that things are way less messed up than we fear!
One of my favourite movies of all time is a NZ flick called 'The Price of Milk'. Just found out there are copies of the DVD for sale online! (Have spent ages trying to find it in shops; duh) A summary of the film will not do it justice but whenever I watch it, it reminds me to not worry that there are hidden difficulties in relationships... because that in itself can create a difficulty
Go well, and I second what AM said above