So what happens if you and a significant other (not married) get jobs in different states?

My significant other and I are both seniors in college, however I am likely to graduate before he does. My chosen career field, while available in my current city, has better options and opportunities on the other side of the country. I do not want to move that far if I don’t have to, but it seems like the best offers will come from there. My boyfriend on the other hand has plenty of very good options and opportunities where we live now. This is a hypothetical situation, but has anyone been in a case where you have to move away from your significant other? If so, how does that work? I’m just so worried and scared about it. I love him dearly and we have been together for 4 years now. We have discussed marriage and even children, but it has been only recently that I realized my current location might not be best for my job. At the same time, just the thought of having to leave him/break up hurts tremendously. I feel like I will have to choose between him and my career which is something I don’t want to do. I used to be happy that I found love so early in my life, but now it feels like a curse moreso than a blessing…...

How should we discuss this? He says it’s too soon to tell what is going to happen. That is true, but I’ve always been one to think to the future and it is very likely that one of us will have to move.