WHERE IS THE LINE?

In our modern society
It's nice that sometimes we
Can share a friendship tender
With one of the other gender
Who wedded to another be.

And a friendship tender
With one of the other gender
Is a real treat
When being sweet
And other traits commend her.

The friendship she shares with him
Enhances her vigor and vim.
She likes it rather much
To be in daily touch,
And problems it tends to dim.

While both the friendship cherish,
Each, more so, his/her marriage.
Now, as ever, platonic,
Their friendship now is chronic
But not to be disparaged.

Their friendship is quite open
As they're ever hoping
To minimize the chances
Of awkward circumstances
With which to be coping.

If it seems they're loping
Down a road that's sloping
Toward the brink of flirtin',
We can be quite certain
That they do no groping.

Though not a rule bender,
Each day of the calendar,
Each finds it's no bother
To be to the other
An e-mail sender.

Good this seems and fine.
But could it undermine?
Before affections wander,
It might be well to ponder
Just where is that line?