Shakespeare is happy to forgive his lover having an affair in this sonnet. Fair play to him.

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Sonnet 57

Being your slave, what should I do but tend
Upon the hours and times of your desire?
I have no precious time at all to spend,
Nor services to do, till you require.
Nor dare I chide the world-without-end hour
Whilst I, my sovereign, watch the clock for you.
Nor think the bitterness of absence sour
When you have bid your servant once adieu;
Nor dare I question with my jealous thought
Where you may be, or your affairs suppose,
But like a sad slave, stay and think of nought,
Save, where you are how happy you make those.
So true a fool is love that in your will
Though you do anything, he thinks no ill.