I suppose that, given this is a fantasy genre, the squirrels have an exceptionally high fertility rate.
Furthermore, the "pull-out" method doesn't guarantee a 100% prevention of pregnancy (it has a 78–96% success rate in preventing pregnancy, meaning there is still a significant risk). It’s also likely that they’ve already tried other methods, but none have worked.
The squirrel does indeed have a large family, and given its poor financial situation, how could it possibly have many options.
In my experience—though not during sex—while I was reading BL manga (alone in my bed room), I heard a whisper "What are you doing?" I replied, "I'm reading BL manga; why? Do you want to read it too? Here, I'll show you." I found some smutty BL manga and scrolled through it rather slowly so the ghost could read it properly. After that, I was never bothered again.
The uke PRACTICES THE BLACK HOLE TECHNIQUE, seme think that while drill in (╯°Д °)╯╧╧