The challenge to separate from each other is not to be underestimated when both sides have attachment issues.
I'm also happy to say that he totally regrets not coming on the trip.
Of course you missed him but there is the upside to him having time and full responsibility for himself. It allowed you letting go of carrying some of his responsibilities. Temporary separations like business and vacation trips can really help here rebuilding a stronger sense of self on both sides. Natural, healthy and relatively painless boundary restoration.