Following the first time

Following the first time that we slept
Entwined, I ceased to notice certain things.
Jokes are still amusing, but there clings
To every laugh a cold caress which kept
Me from bursting out of mirth. A walk
In woods becomes a sprint around my copse-
Like mind; sun can only touch the tops
Of trees, which harbour hot thoughts, brood, and balk
Wincing at the breeze of lighter things.
And though I try to entertain your joys,
Your marginless vast envelope, your wings,
Span out my dimensions, drown my noise
And smaller lives. Why am I weary? Us.
Suddenly everything is serious.