Not sure how small or big you are talking. But like breaking dates or not coming to a dance or wedding when you said you would. Or the bigger scale like with social laws. All have been broken and or changed and some need changed and maybe some should not. But I don't think they were made to be broken when started.
Just about all 'social contracts' are made to be fair in the time when they are made. When times change they need to be re-negotiated :) The side that have gained advantage from the changing times rarely feel the need for such negotiation (eg: "of course the Lord of the manor should have 'Droit de Seigneur' over any commoner maid who marry in his realm. The best seed need to be spread.")
Thriftymaid 