Maybe next time, don't put it in the fridge. Let it cool down naturally. Sometimes, cooling down too quickly when doing emulsified butters, it messes with the emulsion. Another reason is maybe you whipped it too much. Sometimes that breaks an emulsion too. This is what I do: Once you get your water and oils emulsified really good, let it sit, and only use your stick blender periodically as it's cooling down. Once it's cooled to room temp, add your fragrance and preservative. Stick blend some more to incorporate. If you want a more whipped consistency, I would whip it a bit with a kitchen aid or whatever you have, once it's cooled down. But don't over-whip. Or you might get more cottage cheese.