How to use the prefix “un”

I love an old man with grey hair.
His complexion is  rugged yet fair.
I made him some biscuits.
And we decided to risk it.
But do far we’ve not dared to go bare.

I feel it’s my  heart he adores
It  pounds as we lie on the floor.
We could go to bed
But that’s  sinful,it’s said.
And I don’t wash the sheets any more.

I think we should marry next week
As the outlook fert’ angina is bleak
I don’t want to  die
As in sin I lie.
As a passionate old wife I can streak .

But should I get married in white?
I may be an incongruous sight.
For as I am pale
And feeling un-hale
My appearance may bring down a blight