The whole "university fees" spat was so naïve and dim.
The LDs had to carefully marshal what little advantage they has as the minor party in the coalition. A coalition they had entered into under the banner of "best for Britain" to avoid the instability that minority governments that 2017-2019 showed is possible.
With that they selected the core principle - which was electoral reform. And even that was almost a price too much for the Tories (who, if memory served had to be whipped to support it).
Having extracted that concession, anything more - e.g. fees - was too far.
It's worth bearing in mind the coalition was a formal public contract. Again the LDs insisted on that in order to make sure there was no "misunderstanding" over the parliament. And that contract did not allow the LDs to refuse to back the Tories on key measures.
I get that LD voters may have been disappointed. However rather than accepting there had to be some give somewhere, the ones that flounced off and gave us David Cameron in 2015 have a fuck of a lot to answer for. Maybe they've grown up a bit ?
(For the last 28 years, I have only voted Labour. That's because my constituency is quite a safe Labour seat. However I will quite happily vote LDs in May.)