This is from an outsider to UK politics but it seems weird to me that we didn't see the Lib Dems or some other smallish party position themselves as the party of "We won't Brexit" and pick up a lot of the Remain votes?
Given that the current Labour leadership are quietly pro-Brexit and that there is unlikely to be an election anytime soon I don't think there is any chance of an electoral solution to this problem.
Or once a governing coalition is formed is it "locked in" until new elections?
Nick Clegg rather infamously signed a very public pledge to vote against increases in tuition fees[0]. Then voted for tuition fees in coalition.
[0] https://www.theguardian.com/politics/2010/nov/12/lib-dems-tu...
Also the media does not cover what the LibDems are saying much at all. They don't even report on Labour much, just the various factions of the Conservative party. I can't even blame the media. The smallest change in the internal alliances of the Tories can have a huge impact on the country right now. What Labour or the LibDems say has exactly zero effect until the next election, unless they can somehow get together with some Conservatives.