Hmm. That's one way of putting it. Another way would be that the reactionary forces of the old aristocracy reestablished themselves, then created a fairly repressive regime to stamp out the ideas of "liberty, fraternity, equality," even as a middle class began to emerge who wanted some voice in their government, leading to the Revolutions of 1848.
I listed to a BBC History Podcast a while back interviewing the author of "The Phantom Terror" a book about that period. Here's a Wall Street Journal review of the book.
One of the things he talked about was that in Austria censorship was so severe--with all foreign mail opened and read by government agents--along with banning of foreign books and travel restrictions, along with a massive network of spies and informers and secret police, that a part of Europe that had been among the most enlightened and advanced became a backwater, a status it more or less retains to this day.
As for "reactionary forces of the old aristocracy," I trust that you do not include the titled ancestors of "Phantom Terror" author Adam Zamoyski. They were long prominent in Polish politics as aristocratic advocates of reform and national independence. Indeed, many European aristocrats were advocates for liberty.
In any event, the proximate cause of Europe's decline was not the relatively benign Revolutions of 1848 but the massive destruction of WW I and WW II and the ensuing rise of the United States as a world power, with Europe divided by the Cold War and the free half reliant on the United States for its security.