She's 22 and not yet been on her own. She's going to want to assert her own sense of self and explore what life has to offer. That's healthy. That's good for both of you. You wouldn't want to be with a woman who didn't know herself or have individual interests - that's a recipe for disaster and pain.
There's no point blaming yourself. You married young: you're both still learning what marriage means. You are learning, and she is learning.
Just remember you are on the same team and you love her. Loving her, there's going to be times where she does things you don't understand. It's important not to blame yourself when she does. It's important to be able to support her in her decisions. Sometimes, that means swallowing it up. Letting it be and trusting that things will work out as they should.
You can't control everything, not even if this marriage will work out for the long haul. That takes two - you'll have to see how her side develops.
What you can control is yourself. You can decide: I will be the best man I can be. I will love her even when I am shaking inside and scared she is leaving me. I will keep my dignity. You'll never have regrets if you do this - no matter how things go down.
So give her a kiss and wish her a happy vacation, and tell her you love her. Then, go have a great time with your friends. Or doing something you like. It'll be good.
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