Why does he seems to be uninterested?

Multiple times he is stealing glances from me. From far away, he is looking at me without looking far away. When we are close, I feel that he watches me. He makes effort to hold door for me and looks at me smiling while I’m passing him. When our eyes meet, he looks at and smiles at me. After all of these, I decided to meet with him. But he was so calm. He asked how I am. I explained smt. He asked some questions. I asked him how he is. He only said he is fine by a bit shaking by head. How should I interpret this?

Why does he seems to be uninterested?
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