I didn’t interpret it that way at all. That Clooney’s character does not get the girl doesn’t validate his philosophy.
He learns to care about other people, to put himself out there. And we know he’s taken the lesson to heart, even if he’s personally disappointed, because he writes a recommendation for Kendrick, and he gives a bunch of miles to his sister for their honeymoon. He does all of this after he is rejected by Farmiga.
It’s not an unambiguously happy or sad ending. But I’m much more optimistic for him at the end of the movie than the beginning. He’s willing to take chances that he never was before. He has rejected his own bullshit sheltered philosophy and he’s looking to the future.
The scene where the main characters are eating in a pretty nice restaurant is actually the Cheshire Inn restaurant located in St. Louis. It was a pretty swank place back in the day, but has been closed for the last 6-7 years. I went to an auction they held there last year and the place was pretty decrepit. It was pretty funny thinking of a bunch of Hollywood stars in a place that stunk of mold and piss.