Yes, people in their early 20's think they are now an adult and mature and ready to handle a lot of things. What "changes" a person is life experiences and learning how to be independent. We all learn by doing and experiencing and there are most definitely things one chooses to do only to find out they are not fulfilled and happy with their choice. You are right at the age where you are learning to make your own choices too, learning that while others have their opinions wants and needs, you are beginning to really think about what "you" want. Notice I used the term "learning", that's important because some people never actually learn how to make their own healthy choices for themselves and actually engage that choice. Sometimes, without even realizing it a person ends up choosing around their partner's wants and needs and then without realizing it they end up living their life around their partners wants and needs and never got to have their own sense of growth and accomplishment in their life.

Honestly, now is the best time to think about what "you" want and what you have shared is you are not happy with your career choice. This is important because people can get trapped in the wrong career for a lot of years and remain unfulfilled and unhappy. It's much better to have a career you "love" engaging in because it's less likely to become a ball and chain for you and much more likely to settle you into a sense of fulfillment instead. Well, right now you are young, you have not committed to a marriage, you can wait to have a child too so this is when you should be thinking about what career you really want. Also, what is your education and what do you have that can connect you towards going in a more rewarding direction?

You don't have to get married either right now. You can spend time on yourself first and you may end up realizing that the partner you have right now is not really someone you want to devote your life to.