What does it mean to say someone else is singing?

"Say someone else is singing" means: good at pretending, good at acting, and can change into any character at any time.

Tell me about my deskmate’s experience:

My deskmate, she usually seems nice, but no one really understands her. Including: her character, way of doing things, etc.

Later she fell in love. She told me about falling in love. Maybe it was because she was so happy that she couldn't help but share it with me. Her boyfriend studies computers, is a straight man, and is very calm. Because my deskmate likes this type, the two of them made rapid progress.

Then one day, her boyfriend said something like this: "Why do I feel like I can't touch you? It's like singing in an opera, there is a sense of illusion." Then, my deskmate asked me this sentence What does it mean? Based on her situation, I said something like this: "Maybe it's because your personality and work are not very fixed, so others can't really understand you and understand you."

Yes, if you give others the feeling of singing an opera, it means that your personality is unpredictable and difficult to control, and your way of doing things is difficult for others to truly understand, which is why you feel like this.