I got him his dream job

I moved across the country for my partner. Things were progressing as they should we lived together and talked about marriage etc. He was starting to struggle with his job, not enough work/life balance so I encouraged him to apply to an open position within my company. I built him up to the hiring committee, my friends were his references, I coached him for the interview. He got the job! Then, after his first day of work, he dumped me- after 4 years of dating/being in a serious relationship. He said he thinks we arent compatible anymore and this new job is changing his life/making him stressed. I am completely in shock. Now, I have to see him at work. My heart is completely broken, I am so lost I cannot imagine what was going through his head.