You can certainly cook rhubarb without sweetening of any kind, but that wasn't really your query was it?
If your DH likes to try rhubarb without any sweetening that is his affair. Like you, and most of the rest of the world, I certainly am not able to eat unsweetened rhubarb.
Cook your usual amount without any sugar, dish half of it for him, add sugar to the rest for yourself, bring it up to the boil again.
Make sure you know which plate is which, put his in front of him and watch his face when he tastes it. Don't put a spoonful into your own mouth until he has tried to swallow his first mouthful, as I guarantee the sight of his face will make you laugh and choke if you were trying to eat or drink at the same time.