phantassy - i agree with delia about writing it down. i was asked to keep a journal. i am not much for analyzing my feelings and writing them down, it somehow makes them too real. at first it was hard to do. actually sometimes it still is....
however, writing in the journal always seems to have a positive outcome. it gives us both time to reflect on the issue. i get to write down the things that are sometimes difficult to say "in person." he now has a way to see things from my point of view. usually, in our next time together, he'll find a way to bring up my concerns and it always makes me feel better when we've worked through that.
by the way, keeping a journal isn't always about the concerns...it's solidified many of the positiive aspects of the relationship as well.
good luck! cookiecat