<human>: Could you distill the essence of the text into 1-3 sentences?

My girlfriend (20) just left me (19) for another guy(25). This was one of those scenarios where there was one of her guy friends that I was kind of suspicious of but didn't really push the matter because she has so few friends. All of my future plans involved her, if I had the money I would have asked her to marry me. I tried so hard to make things work and now my future is ruined. How do I move on when my idea of the future and a lot of my past and how I see myself is tied up with her.
<bot>: My girlfriend of 5 years left me for another guy. how can I manage the memory of past and rebuild what I wanted in the future?