You want an explanation but you want to frame the question in too simple of a manner.
Was the ACA imploding, no.  The ACA was on track to have a lower increase, but still an increase, this year.  That was before Trump began working to weaken it by spewing his dung, threatening to stop payments and eliminating funding for getting the word out for enrollment at the end of the year.  The net effect of the REPUBLICAN actions on the ACA was to instill uncertainty into the market and the insurance companies have responded with another big jump in rates.
It wasn't Republican lies so much as Republicans usual complaining that government is the problem and then making it the problem.  Now that the GOP is in charge of all three branches of government it's their job to make it work and they seem incapable of anything other than messing it up.