A good example of a negative consequence coming from a well-intentioned policy is the way that the current benefits system addresses the issues of household economies of scale. An economy of scale occurs where it is cheaper to buy a lot of something and share it between people, than it is for each person to buy their own share independently. A simple example is utilities, where it is cheaper to heat one home and share the cost than to heat two homes. The current system recognises that single people need more money to meet costs like these, and so they receive more than half the amount for a couple who are expected to be sharing bills.
Superficially this makes sense. However, since this reduction in support only affects couples rather than two single people living together it becomes obvious that this is going to force people to live apart and increase the demand for single tenant housing, with inevitable negative effects on family life. By unfairly targeting people in relationships this policy becomes discriminatory and needs to end.