My wife and I have been married for five and a half years now and have had a pretty good marriage. Our sex life had been good until recently, when it got to be a routine thing and kind of boring. I took a job that required us to relocate about an hour and half away from where we lived, so we moved. We had a hard time finding a baby sitter in the new place, so my wife invited her younger step-sister to come stay with us until we found a sitter. Her sister loved the new area and decided to stay with us until she found her own place to live. After a month, she was still living with us and she and I were getting quite comfortable. One rainy day while my wife was at work and the kids were in bed, we started to cuddle up on the couch. We started to flirt, which let to heavy kissing, and the next thing I knew she was unbuttoning my pants and giving me the best the oral sex I have ever had. After a few minutes of that, I pulled her back up and returned the favor. For the last two months, we have both been having the best sex of our lives. The best part is we are both very open with our communication and agree that this is a no strings attached relationship and that I still have sexual obligations to my wife.