If I hear or read another person complaining that "I didn't vote Lib Dem to let the Tories in" I think I might grind my teeth to a pulp.
I remember Nick Clegg saying that he believed that the party with the most votes and seats should have the opportunity to form a government. That was the deal the Lib Dems were offering. Complaining because the leader of the party you supported stuck to his word can tend to make you sound like a sulky arse.
The Labour Party doesn't have a moral right to be the government of first choice. They don't have the right to demand that all other parties join them in an alliance to keep out the Tories. If, as a voter, all that matters to you is getting a Labour government at all costs, then vote Labour and take your chances.
All that aside, the numbers just weren't there for a Lib-Lab coalition anyway and given the sharp contrast between what seemed to be constructive Lib-Con negotiations and what seemed to be stubborn Lib-Lab negotiations, I don't think it would have been anything other than a shambles even if the numbers had been workable. The ideological differences on civil liberties between the Lib Dems and Labour are so severe that I don’t think they could have been overcome. On the other hand, any ideological differences on spending between the Lib Dems and the Tories have probably be narrowed significantly by the need to address the public sector deficit.
I think we’ve got the only outcome which was either sensible or workable.