The secret nobody understood

Your family has one rule:
Never go into the abandoned greenhouse at the edge of your estate.
They won't tell you why. Only that it's been locked for twenty years.
But on your 17th birthday, you find a key on your windowsill.
Old. Silver. Cold.
So obviously... you go.
Inside, the greenhouse isn't dead like it should be. The vines are alive. The flowers bloom in colors you've never seen before. And in the center, sitting calmly on the cracked marble fountain, is a boy you've only ever seen in your dreams.
He looks at you like he's been waiting.
"I was wondering how long it would take you," he says.
You don't know how he knows your name.
You don't know why the plants lean toward him like they're breathing.
And you definitely don't know why your family sealed him in here.
But when you try to leave, the door won't open.
And he quietly tells you:
"They locked me away for loving the wrong person."
Then he looks at you.