I think media, or maybe just TV, since there are childish men in many a movie, doesn't explore as much the idea that this issue of reaching the stage where you expected your life to be done or formed or to make sense, as a male. There are childish men on TV. But that's often viewed as a character component and not something like Greg worrying about who would look after his dad is he left his hometown to go off to the college of his dreams, or of there was any point in doing so at his age. Trent was played for laughs, but also made a subtle point that some of the very things that Rebecca did last year (and okay this year too), come off with an added layer of creepy when done by a man.
And Josh. Josh, much like Rebecca, doesn't really know that he's searching. He had a plan. He was happy with his life and because for so much of his adult life he had been with Valencia, he hadn't really noticed that he'd spent the year finding women who he felt like gave him purpose.
And yeah, to finish this out, we've got to get into the season finale. So, do I think Josh will be a great priest? No. (Teacher, quite possibly as his camp and coaching experience have shown.) But for all the differences between Josh and Rebecca, they both had been using each other for validation. That Josh realized that enough to not go through with the marriage is great. (It would have been nice if he had realized it enough to tell Rebecca to her face, but baby steps.)
I hope Josh, and even Trent, find a focus or path that makes them happy. And again, the lesson that dream ghost therapist imparted in season one is still true, falling in love is not the only way to find a lifelong goal or even a lifelong love. Josh becoming a priest to get out of the bad habit of turning to the nearest pretty girl for validation is still looking for an external person (be it more godly) to provide him a goal.