Counting cost of odd love triangle

I'M done with paying my girlfriend and her sister for sex.

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They know I'm weak and are taking advantage of my thirst for no-holds sex.

I own a flat in the city. My on-off girlfriend of three years comes and goes as she pleases.

Whenever she's short of cash, or food or drink, she turns up here and expects me to drop everything literally. She strips off and says: “Let's go to bed.”

She suggests all the filthy things we can do from bondage to spanking.

I try to resist her, I push her away and say: “No thanks.”

But I'm a red-blooded male and can only hold out against so much when passion is offered to me on a plate.

She manages to wear me down and arouse me even when I’m not in the mood. She rubs herself all over with baby oil, talks dirty, promises the world and makes me feel obliged to service her.