I think my female guinea pig wants some romance?

I got my piggie about a month ago, and she's the sweetest thing. She always cuddles with me and comes to get picked up when I open the cage.

It's getting colder here so I decided to get another piggie to keep her company, so I bought another female to prevent mating (can't handle a litter). My older piggie (Misfit), is playing dominance and show off with the new girl... and since I got her, Misfit has been acting odd. It's been about a week.

Whenever I touch her, she purrs and stretches out her body, and lays flat on the floor purring. I also noticed over time that when this happened, her private area completely pops, as if she wants to have sex. I did some reading, and it turns out... she does.

What the Hell can I do now? I have a horny guinea pig on my hands, and it's getting a bit odd. I want her to be pleasured, but I definitely can't do this whole pregnancy thing- and I don't want to put her through a neutering.