The things is, 22 isn't too young to get married. People get married at 22 all the time and make a go of it. I think the issue is that, a lot of changes happen to you in your 20's. It's when you grow and figure out who you are as an adult and how you're going to make your way in the world. You can certainly do this while married to someone WHO IS ALSO GOING THROUGH THE SAME THING. The issue I see with Bekkah and Arie is that Arie isn't feeling it all out anymore. He's ready to settle down with someone who's done with that phase too. If Bekkah is ready to get married, she's not ready to marry Arie. She needs to marry a guy who is 25 or younger and wants to go rock climbing on the weekends, dancing in clubs, traveling around, seizing the day, etc. Arie wants someone who is fun to be around and who he enjoys talking to, but he doesn't seem to want to be out galavanting around taking advantage of his youth.
My point is, Bekkah might be ready for marriage at 22, if she meets and falls in love with the right person for her, but it's not Arie.