I hope LaTeeDa might post on expectations. I have learned a lot from her posts about it.
In a nutshell she talks about how having expectations is not always the problem, but having expectations of someone in active addiction can be. There is more too it but for me that really helped.
I had expectations of the role of a "husband," the person I had it of though was actively in his addiction and it was not very reasonable that he could meet my expectations in that capacity.