Divorce?

We're only 22, we've been married for 3 years. I love him so much and I can't imagine what it would be like to lose him. But neither of us are happy. I don't do things that he wants me to do, he doesn't do things I want him to do, we fight over the same things over and over again and nothing ever changes. I know sometime down the line, we will go our separate ways and I am dreading it so much, even though I know I'd be much happier with someone else. He's the only guy I've literally EVER been with so I don't know how to live on my own. And I don't know how I'm going to be able to cope with losing him and eventually seeing him be happier with someone else. I know that's selfish, but I love him, I'm just not happy. I know for a fact that I love him way more than he loves me.