Our economists don't want to fix the SEK because it helps our exports and to hell with the citizens.
We've had a neoliberal control for the past 25 years and everything's gone to shit. People keep voting for them tho, because fuck the taxes that pays for everything we take for granted, apparently.
I don't think they need to do it, the ECB or the Commission or EUCO never showed any sign of trying to force their legal obligation to join, so doing nothing is enough not to join. But in any case the weakness is becoming perennial and that's problematic for Sweden.
Not necessarily destabilised, but Sweden has deliberately opted not to join the European Exchange Rate Mechanism which purpose is to stabilise currency exchange rates.
Sweden is by law bound to adopt the Euro, but by choosing not to join the ERM II, Sweden by extension can't join the Euro because they technically don't fulfil the requirements.
This is of course a simple loophole that could be closed by the EU, but there hasn't really been much political will to do anything about it.