The second factor that you have mentioned, about the odd sort of co-dependence is actually undergoing a rapid transformation. Several women these days are extremely comfortable with online interactions and things like twitter, facebook has actually created avenues of finding emotional support from someone other than plus one to be much much easier. This is actually creating some strange kind of issues which I don't think even existed 5 years ago. In fact, I might make a guess (based on empirical evidence around me) that there are more women who are very active on twitter/fb than men, among the people I know.
The realizations that you have shared are deep and insightful and they will certainly help me in my journey. I have been on/off in a relationship since the past two years and it has been very hard trying to make sense of where it is headed. Sometimes I feel like I would like for it to continue forever, and then there are times when I know that it won't last more than a few weeks.
Your point 2 is well taken, though right now I am in the phase which is "even though they can, at times, be really hard".
It was wonderful to know that you have been in a 17+ yr relationship and things are working out so beautifully!
Thanks again, for sharing.