A great account, StitchwitchD! I really value real-life experiences with poly - no book can illustrate so well the various practical pitfalls of relationships of this nature, so love to read other people's experiences.
Very pleased that these have been learning experiences for you - I have seen too many stories told of people who repeatedly get themselves in the same situation, blame the others and then complain about why they can never be happy.
I also think there are many who haven't got themselves worked out yet to the point where they can have a healthy, open and honest relationship. I mean I believe that we never have everything worked out about ourselves and that the journey continues, but there is a certain basic requirement that is needed to avoid your partners not knowing whether they are on head or horseback with you.
Based on what I have seen (and been guilty of myself, I'll admit) is running into relationships without really having any sort of framework and "winging it" - for some that might work, but when you are in a poly/mono arrangement, or with people that aren't really sure if they are mono or poly I would suggest that it rarely does.
"Listen, or your tongue will make you deaf." - Native American Proverb