Generally speaking I communicate very effectively BUT if I'm really angry or am totally surprised by a particular situation I get moody & not very nice to be around.
These times I will tell a person that I've got something on my mind & they can read my LJ when I've finished it.
When something is really bothering me I take to writing. It's very cathartic for some reason. I can let go of the conscience thought process & just let the words flow whether it's via a keyboard or pen & paper.
It sounds like all Thunder, & the rest of you, needs to do is vocalize that he's processing & needs to be alone. Is that something he would be comfortable doing?
There are as many ways to do polyamory as there are people practicing it!