The party has lost morality with its voters probably stemming back from letting the students down with Clegg going back on his promise on student fees.
I think the LibDem's problems extend further back to when Clegg first became their leader.
Under Charles Kennedy I strongly supported the LibDems as I saw them as the only major party occupying the slightly left of centre ground, and judging by their electoral success at that time I wasn't the only one.
However when Nick Clegg became LibDem leader it became obvious that the LibDems had decided to arrive late to the neoliberal party, and that Clegg was simply another repackaged Tory like Blair.
The 2010 general election should have been watershed for the LibDems. Labour by then had been in power for 13 years, a very long time in British politics, but more importantly, the Conservatives were seen to have very little credibility in the eyes of the electorate, indeed they failed to win the election.
This waiting open goal for the LibDems should have resulted in them enjoying a huge groundswell of support as the obvious alternative to the two discredited parties. In the event the LibDems failed and pretty much received the same vote as they had received 5 years early under Charles Kennedy.
It was clear that under Nick Clegg the LibDems had failed to significantly convince voters that were able to offer an alternative to the other two discredited parties.
And as it turns out they were right ..... as Clegg went on to prove.
Making Nick Clegg leader was the first big mistake the LibDems made. Entering coalition with the Tories was just the follow up mistake which finished them off. IMO