Maybe you are not really an emotionally connected kind of person. You have no idea what your loved-one is feeling and they don't either. Or your emotional intelligence may be high, but you are trying to validate someone who is intent on avoiding their emotions. It seems like your attempts to observe and describe emotions go over like a lead balloon. "No! I am NOT angry!" Or, "I'm not sad, you're sad." Or a blank stare.
Try this: Put the distress in the situation, not in the person. Then use words that communicate some type of discomfort, not an explicit emotion. You may not know exactly what the other is feeling, but it is apparent that there is distress. Note how a situation seems stressful and it is less likely to result in defensiveness by the other person because it is not perceived as self-referential.
"I cannot imagine how difficult that situation must be."
"It seems like that would be annoying."
"I can see how hard that would be."
"It must be a very distressing situation."
"That environment seems so stressful."
"Those conditions must be very challenging."
"Being around that person has to be painful."
"Wow, it sounds like everything is pretty tense there."
"Those circumstances seem really unpleasant."
"How frustrating that sounds!"
The essence of this type of validation is seeing how a person's distress makes sense because it was caused by a distressing situation. You don't have to know much, just make your best guess...and wait for more information or ask. When validating, always be open to understanding the other person's perspective with even more clarity. Be open to making a mistake and learning from it. Keep in mind, you probably want to be effective more than you want to be right!