Citation needed. As far as I am aware, NATO spending was never an issue until Trump took office, and even then he exaggerated the deficit.

https://www.factcheck.org/2019/12/factchecking-trumps-nato-remarks/

"The president wrongly claimed that other NATO member countries’ spending on defense was “heading down” three years ago. That spending went up in 2015 and 2016. And he claimed countries that spent a low percentage of their GDP on defense were “delinquent.” They don’t owe NATO, or other countries, any money."

So while this was a longstanding complaint from Trump, I do not think you should conflate Trump's pronouncements and declarations with US national interest.

Indeed, the financial success of the EU was predicated on two things: cheap gas from Russia and cheap national defense provided by the US.

Most US Presidents were aware enough to appreciate that the wonderful social welfare states that the Europeans established could only afford to exist as long as the US picked up the tab for their defense - which has always been the case.

This devil's bargain - ie, lower defense costs thanks to the US in return for undying fealty to American interests - is what has helped the EU to become what it is today.