What did I do wrong? How can I fix it?

Hi all! So I have a conundrum with my boyfriend. We met at work 6 years ago and have been together for the past 4 years. i love him tremendously and we have been inseparable since we linked up and lucky for us we have been sitting right next to each other this whole time. Last week I was offered an amazing opportunity which I feel like I can’t and shouldn’t pass up but it entails that I will have to be moved away from to another part of the building. Instead of being happy for me he has sunk into a deep depression and sadness over this and even told me that if I do this he and I will be ruined. He began to ignore me by not talking to me, looking at me and barely being around me. This all transpired in the past few days since i was offered the promotion. i tried to reassure him that i love and care for him and nothing will change that. i reassured him that as long as we try to make things work then we will do just that. i try to talk to him and cheer him up but he is not having it. i feel like he is trying to manipulate me to pass on the position but i dont want to and will not do so. i have a young son and would love to better our lives for us with more income. he finslly called me today and asked me if i truly love him. i told him yes and that I've been saddened by how he's being cold and treating me over my professional growth. he said that is not the case and that he's going through other hardships and i just dont care about him. every time he is sad or upset i encourage him that things will be fine and workout and not give up. he mentioned I've been acting like my usual self at work so how could i be sad. i reminded him that i need to get my work done also train my replacement while also training for my new position. He said my actions show him how i really feel. i am at a loss of words for him. did i do something wrong? i dont know what to do anymore. everything i try or say just backfires.

(sorry for the long post and thank you for your opinions!)

What did I do wrong? How can I fix it?
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