Is it workable or is it the death knell?
Without a great many more details, the only sensible answer is 'it depends'.
It's not ideal that he appears to not have discussed it with you. In our case DH was offered a job on the other side of the world, out of the blue actually at a dinner party, so at least I knew that it was out of the blue.
I would look to the practicalities first, before considering how you feel about the whole thing.
Is it really his dream job, how much does he really know about it, how stable is it likely to be. What outside influences could make it less stable. How long would he be tied to it if it didn't live up to his expectations ?
How good is the pay? Can he (easily) cover the additional costs, including second home, and travel for him to return and you to visit him occasionally.
Also the opportunity costs, for you to have cleaning/ironing/handyman help in the home so that when he is back you can have quality time together and life is not just a round of catchup on chores How comfortable are you both with technology, using FaceTime or whatever and Shari g a diary so you are still in sync.
How good is he with his own company or is he likely to haunt the local pub for company and find the profits get drunk.
How do you feel about being on your own ?
It has worked out really well in our case but I get that it would not be for everyone. I have also worked away for extended periods of time so understand the life and also what it takes to get it to work for me.
Allow yourself to dream a little about what your ideal life would be like. And then see how it matches.