I got married at 21, my wife was 19.
I know how you feel... I went through a phase where I harbored some resentment that I never got to "live life fast and fun" before settling down. It can be hard, but remember that you married your spouse for a reason: You love him and you knew you would be happy with him. Some people spend an entire lifetime looking for love, for a fulfilling and meaningful relationship. Count your blessings and be happy that you found something wonderful so early on. Now you have a much longer time to enjoy your sweetie.
At the risk of giving you TMI, here's a suggestion. My wife and I did this a few times shortly after our wedding because we were both feeling like you're feeling.
Dress up nice and go to bar. Go inside, but don't hang out together. Chat with other people, flirt with them a little (if you're both comfortable with that), and have a good time. At some point, "find" each other and go home together as if you're just hooking up with someone from the bar. I'm sure you know what inevitably follows at home...
Makes for a fun evening and a very satisfying night for both of you.
He hasn't done that yet but he has the desires to.He has lost respect for you. He KNOWS you have no intention of leaving him; therefore he's free to resent you and go have fun. IF he were worried that you wouldn't put up with it, I'll bet he'd change his tune.