I'm madly in love with my boyfriend, but at the same time I want to be single again...what to do?

My boyfriend and I have been together for 2 years, and I love him to death, we have a wonderful healthy relationship and he treats my like a queen (unlike ANY guy I've seen) but for some reason lately I've been dying to be single. Since we've been together I don't go out and party with my friends anymore (because that's just not cool when you're in a relationship, I do still hang with my friends though!) and I am just dying to go get drunk with friends, meet new people, go back to my old fun life. I also have a small crush on a guy that I work with and I just love subtly flirting with him (bad, I know...) and just wish I could hang out with him or any guy-friend for that matter! I would never cheat though! I just feel like I'm too young to be locked down (I'm 21) but my boyfriend and I are such a great match, I could see myself marrying him someday, and I don't think I'd ever be able to find another guy who shares so many interests, treats me so well, and is so honest and faithful so I know I'd regret breaking up with him if I did. What should I do?!