By that logic, "How does loved one dying affect different type of hormones, if at all. Given how sensitive our hormones are, it would be difficult to control only for 'loss of a loved one'".

If you have depression or another condition affecting your affect and your emotions, sure. Otherwise it's pretty obvious to anyone that concepts on orders of magnitude higher levels than hormones being correlated with happiness, or if you prefer, those concepts having a significant effect on the overall action of those hormones.