Little trick, anything that you would use “estar” in romance languages aka Portuguese, use “feel” instead of “be”, it’s just as valid and there’s less misunderstandings.
Also, for your examples, you would never interpret “you are sad” as ser, since ser describes adjectives, it’s always estar. Your ser version would be “you are a sad person” aka “eres un triste” (in Spanish).
Little trick, anything that you would use “estar” in romance languages aka Portuguese, use “feel” instead of “be”, it’s just as valid and there’s less misunderstandings.
Also, for your examples, you would never interpret “you are sad” as ser, since ser describes adjectives, it’s always estar. Your ser version would be “you are a sad person” aka “eres un triste” (in Spanish).