Another superb piece from you again! There is sadness and elegance in your words. I can feel the yearning and longing. The structure actually helped to deliver the message of this poem, at least for me. Greatly done!
The French word 'Douce Caresse' translates to 'Sweet Caress' Using the French wording in the title gives this poem a foreign air from the off.
The way you describe a single and I presume a harmonious note, being 'stripped of music' is excellent. By reducing a whole piece of music to its core note somehow concentrates the feeling; honing it to a definite white hot emotion.
Only this intensity could traverse to and beyond the horizon. I imagine like a radio frequency, only those communicating and tuned into that exact 'love' station will hear what is being communicated. These airwaves in (the sky) is the way the 'sweet caress' can be heard, felt and all importantly maintained.
In life there are and will always be skeptics, but what do they know - after all, they are not tuned in.
Nice touch on the bookends of 'you were there' repeating this phrase gives it power and meaning - You were there - I know this, you know this - we know this!