David Cameron's failure to meet a pledge to give married couples a tax break is symbolic of the Government's "compromise-driven inaction" on tackling family breakdown, a think-tank has said.
The highly-critical assessment of the coalition's first year in power was delivered by the Centre for Social Justice (CSJ) - which was founded by Work and Pensions Secretary Iain Duncan Smith.
And it comes just months after the former Tory leader himself risked stoking tensions with Liberal Democrat colleagues by renewing calls for the state to reward marriage financially.
In a report to mark the anniversary of the power-sharing deal, the CSJ complained that the tax break plan had "moved off radar" because of opposition from the Liberal Democrats.
Ministers had also shown a worrying lack of ambition, it said, continuing Labour's concentration on "picking up the pieces" of family breakdown rather than preventing it happening. "The coalition has committed a paltry £7.5 million to relationship support," it noted.
Grading five key "pathways to poverty" - it gave good scores to welfare reform and drug and alcohol policy although it warned of "alarming signs" the Government was not taking prevention seriously and said benefit caps should be phased in to avoid damaging drops in state support.
School reforms had been poorly implemented and no vision set out for helping people get out of serious debt, it added, and gave ministers just two out of ten on dealing with family breakdown.
Lib Dem leader Nick Clegg condemned Tory plans to offer tax breaks for married couples as "patronising drivel that belong in the Edwardian age" ahead of the general election.
The coalition agreement made clear that his party's MPs can abstain in any vote and though Mr Cameron has said he intends to press ahead, the move has so far remained on the back-burner
The CSJ said: "Although marriage is no magic bullet, the evidence shows that children born outside wedlock are far more likely to grow up in poverty and experience poorer life chances. Some of the vital measures committed to by the Conservative Party in opposition appear to have been watered down during Coalition negotiations."