Being the Killing Time Girlfriend is a very thankless job. Generally, your role is to act as a long-term training wheel for your boyfriend. He strings you a long all throughout college and grad school.
Finally, he dumps you after 7 years together. You stayed because you thought that he would eventually marry you. After all, you did put your time in. Alas, he viewed you as a way to pass time while he prepared himself for his future wife.