Kpopp's sweater analogy is true, but only for new relationships. Yours had been established for years and so it doesn't really apply to you. In fact, I may know Kpopp personally, and if he is who I think he is, my old friend from Stanford, than don't take his advice. He was in a long term relationship with a Korean woman and yet he continued to meet other women. He tried to pick up on Camille, and then Camille figured it out and she alerted all of his friends on MySpace that he is a womanizer. I continued to be his friend, but his girlfriend deleted all of my emails for a month. It was hugely annoying, but also I felt sorry for her because her boyfriend was a loser! Tell Kpopp to try to be monogomous for one year and then watch him to see if he can do it.
I am not a counselor, but when I read your letter my first gut feeling was that you didn't give your girlfriend what she needed. You were extremely affectionate by writing beautiful poems and celebrating your anniversay on a montly basis, but you missed certain milestones in your relationship that she probably expected.
Most women expect to be offered a marriage proposal within a year and a half. Their family's religious background influences their expectations a lot, and so expectations are different from one family to the next, but have you ever met a woman who wanted to wait for 3 1/2 years to get her marriage proposal?
When you decided on creating an online business instead of going to graduate school or getting a job, it sent a message to your girlfriend that you were not planning to get married any time soon. She probably figured that you planned to spend the next few years trying to get your start up off the ground, and that she would have to wait that much longer.
She's a junior in college and all of her friends are searching for The One, and if the college offers graduate programs than she has watched many of the older students get married. In the meantime, she's being left out.
If you want this woman back, keep your line of communication with her open, apply for graduate school to show her that you plan to be responsible, and propose to her.