My wife is pregnant and has returned to her hometown, so my wife's sister came to our house, thinking that she might be in trouble. However, that was just an excuse, and she came to me to relieve her desires that were not going well with her husband. While I was getting a massage without knowing that, my sister pressed her breasts against my body and I got an erection without thinking, and she asked me, "Aren't you pent up?" I tried to refuse, but...