The decision of Nick Clegg's right-hand man to go public with a threat to resign over the changes being imposed on the NHS is a sign that the Liberal Democrats are feeling the strain of this marital yoke. Norman Lamb's outburst was the equivalent of shouting an ultimatum at your spouse across a crowded pub.
The concerns being voiced about our health service are valid: the public is increasingly worried about the future of an institution that the Conservatives failed to treat properly the last time they were in power.
But the problem with deploying this tactic is that it makes it impossible for the issue to be win-win for both sides of the coalition. If the Conservatives back down and see sense on the NHS, David Cameron looks like he has been shamed into it by public posturing from his junior partner. But if the Prime Minister digs in and refuses to make meaningful changes, the Lib Dems will look even more impotent than before.
This is a far cry from the 'in for a penny, in for a pound' strategy Clegg espoused before the going got tough.
The kicking that the Lib Dems took over their broken promises on tuition fees has clearly had a significant impact. In the wake of that debacle, the Lib Dem leadership briefed the media that they were going to start demonstrating the ways in which they are distinct from the Tories. No-one expected such displays of difference to be quite so ham-fisted.
This is fuelling considerable resentment from the Tory backbenchers who already feel their new relations get away with too much. Tory MPs have had to endure giving up plum government jobs for people they used to deride as pompous, muesli-crunching charlatans.
They could just about take that ignominy when their new partners gamely acted as human shields against the rocks being thrown at them by the public.
The whole arrangement will prove harder to bear if the muesli crunchers decide they would rather lob the odd rock themselves.
John Woodcock is Labour MP for Barrow and Furness, and a former spokesman for ex-prime minister Gordon Brown.