I think the song is about a man who is in love with another woman, but both are in another relationship making it an impossible love. When he talks about the chains that keep them apart, I see it as being attached to someone else or being married. Therefore, he knows it's impossible and nothing can happen.
"Je n'avais pas vu que tu portais des chaînes. À trop vouloir te regarder, j'en oubliais les miennes."
"I didn't see you had chains. While looking at you, I forgot about mine."
I think the song is about a man who is in love with another woman, but both are in another relationship making it an impossible love. When he talks about the chains that keep them apart, I see it as being attached to someone else or being married. Therefore, he knows it's impossible and nothing can happen.
"Je n'avais pas vu que tu portais des chaînes. À trop vouloir te regarder, j'en oubliais les miennes." "I didn't see you had chains. While looking at you, I forgot about mine."