I need advice on how to move on.

[TinCow]

Nah - it can and does happen. It happened to my Aunt and Uncle - they met at 16 and were married for something life forty years before she passed away

Sure, but it's a lot more rare now than it was when your aunt and uncle met. In the US in the 1950s, on average people got married significantly younger than they do now. In 1950 the median age was 22.8 for men and 20.3 for women. In 2011 it was 28.9 for men and 26.9 for women. This age shift is significant, and it moves marriage into an entirely separate point in life. At 20-22, you are still a child in many respects. You have finished growing and are legally responsible for yourself, but you are only just beginning to experience life as an adult. That experience changes you significantly, and results in major personality changes for most people. By the time you're in your late 20s, you've finally started to stabilize again and figure out who you're going to be for the rest of your life. Relationships that are established before this personality shift are much less likely to last simply because the odds are that at least one of the partners will change in such a way as to no longer make each other compatible. In addition, in modern society is is pretty normal for both partners to work full-time throughout their lives, particularly prior to having children. As such, there is also the issue of divergent career paths to split apart couples that are just entering the job market. Couples that meet several years after entering into the job market are far more likely to have compatible career situations that make long-term relationships easier to manage.

[Philippus Flavius Homovallumus]

Sure, but it's a lot more rare now than it was when your aunt and uncle met. In the US in the 1950s, on average people got married significantly younger than they do now. In 1950 the median age was 22.8 for men and 20.3 for women. In 2011 it was 28.9 for men and 26.9 for women. This age shift is significant, and it moves marriage into an entirely separate point in life. At 20-22, you are still a child in many respects. You have finished growing and are legally responsible for yourself, but you are only just beginning to experience life as an adult. That experience changes you significantly, and results in major personality changes for most people. By the time you're in your late 20s, you've finally started to stabilize again and figure out who you're going to be for the rest of your life. Relationships that are established before this personality shift are much less likely to last simply because the odds are that at least one of the partners will change in such a way as to no longer make each other compatible. In addition, in modern society is is pretty normal for both partners to work full-time throughout their lives, particularly prior to having children. As such, there is also the issue of divergent career paths to split apart couples that are just entering the job market. Couples that meet several years after entering into the job market are far more likely to have compatible career situations that make long-term relationships easier to manage.

Well.... A lot of that was true then.

The point is - going into a relationship thinking "this will end in x.... years" is not all that healthy, or honourable.

[Xiahou]

By the time you're in your late 20s, you've finally started to stabilize again and figure out who you're going to be for the rest of your life.

Nah. I don't think you ever stop evolving mentally/emotionally.