The first source quotes from the Pew Report and lifts out the main headline - that EU membership is more popular now among member state citizens. If you read my post in full you'll see I pulled out other headlines from the same report, which I linked for convenience. I note you don't challenge any of the facts I posted, some of which highlight inherent weaknesses in the EU (I'll cover those later).
The second is behind a paywall and cannot be read.
Not sure about the reliability or neutrality of the third, or its source (can't open the full report) but I note from the data that of all the EU28, more respondents distrusted it than trusted it.
In any case, the idea that an institution is stable or not otherwise in terminal decline simply because its members say "hey, it's okay" doesn't hold much water. For example, the Roman Empire did not decline simply because its population lost faith in "the project", it declined based on a number of internal and external factors.
The factors which will ensure the decline of the EU are:
1) A lack of political accountability from its senior leadership.
2) Severe democratic defecit, particularly in relation to the European Commission
3) Excessively large, resistant to change, unable to address external threats
4) Flirting with Turkey, a large Muslim country
5) A resurgence in nationalism and civic nostalgia, with increasing awareness of national histories and cultures
6) Germany imposing its economic model on culturally different nations
7) Lack of border security at the EU perimeter
8) Severe mission creep - it was originally designed to bring together large and prosperous European countries, to defend against the spread of communism and buttress the Eurobloc from external impacts. It has has ended up incorporating a hotch-potch of smaller nations, each with their own agenda.
9) Unlimited free movement
10) Ever closer union is not wanted by many.
For these reasons, I say the EU is in terminal decline.
It is not as simple as asking people who live there if they like the EU.