I have been in the exact same situation 6 years ago. I found a good job that I accepted but my girlfriend found a job abroad the week after. I decided to let go

I have been in the exact same situation 6 years ago. I found a good job that I accepted but my girlfriend found a job abroad the week after. I decided to let go of the offer I had already signed to relocate with her. It sucks big time to call someone and let them down (especially since I called on Christmas :s). But it's much more desirable than joining anyways with after thoughts. Worse thing you can live with is regrets. They'll find someone else in a couple weeks.