You get inured to the side of the bed
You've slept on for years...
Your side...
As fixed as the boiling point of water,
As enduring as Genesis. 
But new needs sometimes dictate change...
Perhaps an accommodation to a new lover,
Who can't sleep, if not on your side.
So you let her have it,
Knowing it's a bargain with benefits.
But you're still no friend of change,
Since now you have to turn your head
And sleep on the other ear,
And wake with your other eye, topside now,
To squint at the clock in the morning,
And how your other arm now
Is the arm bent under your head,
And how your lead leg out of bed now
Was the lag leg on the other side...
And until inured anew...
There's trouble, knowing the way to turn
In the dark to the bathroom.
But, still and all,
A change here and there
Can work out well.