PR wouldn’t fix anything.
If your argument after losing an election is to demand a different system, that sums up how bad your election campaign is.
Take the 2019 election, it wouldn’t have solved anything. The Lib Dems made it very clear they wouldn’t work with Corbyn, tories & brexit party wouldn’t have either. So that leaves teh SNP & Greens but they had a few large policy differences. That’s not to say they couldn’t have formed a coalition but if they all agreed on everything then they would be in the same party.
And again be careful what you wish for, in 2015 under PR. Tories would have been in government but propped up by Farage to give them a majority of around 15.