In it together: The guilty secret of the coalition is the frequency with which David Cameron and Nick Clegg privately agree

Disappointed love can be a bitterly destructive force. When a couple start using their intelligence to identify each other's faults, and each side goes round telling anyone who will listen how he or she has been exploited, one begins to fear that divorce is not far off. Instead of giving thanks for all the things they have achieved together, each partner begins regretting all the things he or she could have done, and might still do, if liberated from this encumbering relationship. Before long, demeaning wrangles begin about the division of property and custody of the children.

Things have not got quite that bad between the Conservatives and the Liberal Democrats. But each party can be seen positioning itself for the general election of May 2015: a process that may seem to involve seeing the faults in its coalition partner. A few days before writing this piece, I interviewed Nick Boles for ConservativeHome, and could not help noticing the tone of disillusion in which he spoke about the Liberal Democrats. Boles, who used to run Policy Exchange and is now planning minister and MP for Grantham and Stamford, is an outspoken Tory of liberal disposition. He was a prominent enthusiast for the coalition with the Lib Dems, and his disappointment with them springs from the discovery that they are not liberal: "When you look at the Liberal Democrats, what I find completely amazing is how they can carry on spouting guff about Gladstone and liberalism, and put Liberal next to their names on the ballot paper, while co-operating with statist Labour to try to bring in a much more draconian system of state regulation of the press."

The Conservatives lament that they have been coerced by the Lib Dems into devising the Royal Charter on press regulation: a measure to which the Tories on their own would never have consented. They believe David Cameron was forced to go for the charter because otherwise the Lib Dems and Labour would have cooked up something far worse, and made the Conservatives look weak and isolated.

Once the suspicion starts that the Lib Dems would much rather be off doing things with Labour, there is no end to it. On entering government with the Conservatives, the Lib Dems lost the great chunk of their support which had backed them in the mistaken belief that they would help keep the Conservatives out of power. This defection was confirmed by the tuition fees debacle, which suggested the Lib Dems could not be trusted to keep their promises. These left-inclined voters tended to go to Labour, which is one reason why despite uninspiring leadership, Labour's support has not collapsed. The Lib Dems are desperate to get them back, which is why they can be expected from now on to emphasise how left-wing they are. Nick Clegg cannot afford to fight the election as Cameron's stooge. 

But even as I enter this world of tactical calculation, I feel repelled by it. Too much political commentary consists of shrewd, or supposedly shrewd, attempts to work out how Clegg or Cameron or Ed Miliband will try to manipulate key segments of the electorate next time. Of course, in a tight election such manoeuvres could make the difference between success and failure. But they also tend to put millions of people off voting at all, or else send them into the arms of parties such as UKIP which appear less contaminated by the assumption that people are just there to be manipulated.