Having To

Having gone so far, she must just go on:
She’s kneeling and his expectation’s great;
Her hand was on his zipper, now it’s gone
Inside, within his boxers; she’d relate
The meaning of her actions, but a glance
From him ensures her narrative’s held back  
For she has other things to hold, perchance
To tease and kiss and lick; she will not slack,
But is intent on sucking, as he seeks
To shelter both his hands in her thick hair;
And, as he clenches, she ensures he peaks:
She carries on until he’s almost there;
Then, without subtlety, she frees his lust -
A viscous serving poured because he must.