In a world where sadness is punishable by death, and the broken-hearted must gather in secret, a singer of melancholy songs struggles to incarnate the true love he's found in his dreams in order to escape the oppression of his waking life.

I love a struggle with the Thought-Emotion Police, too. But as the logline is currently worded, there isn't much of a struggle. The protagonist's only objective goal seems to be to indulge in escapism, rather than overthrow the oppression, liberate himself (and his fellow sufferers).

I love a struggle against the Thought Police. Please give us a clue about the true love, what she does, will she betray him. any moral weakness in either main character would add a dimension of humanity and interest.

"Secretly gathering with others in a world where
sadness is punishable by death, a brokenhearted singer
struggles to incarnate the true love found only in his dreams."

1)
We the reader know they are oppressed from the set-up of special world circumstance.
By using it twice ie: "... escape the oppression..." & "... sadness is punishable by death.."
it can confuse and be repetitive while adding unnecessary info. Keep your set-up as simple as can be.

2)
What is the inciting incident making the hero incarnate the true love of his dreams ??
How did he become heartbroken ??

3)
What is the urgency that forces the hero to act ?? Why now ??

4)
When you imply "incarnate" & "singer", we presume that the hero
will sing this being into existence and be the main premise. What is the after affect of this ??
Is this punishable or is their a time limit ?? What force is acting against this being ??

Hope this helps :D

Tor