On Liberty by John Stuart Mill Chapter 5 Page 32

himself. When a person, either by express promise or by conduct, has encouraged another to rely upon his continuing to act in a certain way — to build expectations and calculations, and stake any part of his plan of life upon that supposition, a new series of moral obligations arises on his part towards that person, which may possibly be overruled, but can not be ignored.

And again, if the relation between two contracting parties has been followed by consequences to others; if it has placed third parties in any peculiar position, or, as in the case of marriage, has even called third parties into existence, obligations arise on the part of both the contracting parties towards those third persons, the fulfilment of which, or at all events, the mode of fulfilment, must be greatly affected by the continuance or