Help me understand this passage

[vkhu]

This passage was taken from the short story "I have no mouth and I must scream". I don't really get what the author is trying to say here, especially the bold sentence. Can someone please elaborate?

"I gave in easily. What the hell. Mattered not at all. Ellen was grateful, though. She took me twice out of turn. Even that had ceased to matter. And she never came, so why bother? But the machine giggled every time we did it."

 

[SoothingDave]

They seem to be speaking of having sexual intercourse. From my brief reading of the wikipedia entry on this short story, it involves 4 men and 1 woman who were the only remaining humans. Perhaps they had a system whereby each man had his "turn" with the woman sexually. She presumably had sex with this man when it was not his "turn."