Journalist Matthew d'Ancona, who wrote the book In It Together, told Daybreak "there is a much greater wariness" between David Cameron and Nick Clegg than when the Coalition began.
Mr d'Ancona said: "One has to acknowledge that, if you use the marriage metaphor, Cameron and Clegg are still together - they've stuck together for the kids if you like.
"It's impressive because there are tensions between them, they are much warier of each other, but they are still in the same political house."
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