I agree, communication is necessary.
For me I guess I was thinking in terms of myself-well I know I was, because I was expressing the situation I had.
I am VERY GOOD about communicating what I want/need before the fact.
Everyone in my life knows that I expect that both my DH and my BF (now ex) are BOTH fully responsible to me and the family and I to both of them and the family in all those ways.
BUT-there is no way to know what the expectations are if you don't discuss it in advance and I totally agree with you, there is no replacement for communication.
"Love As Thou Wilt"