Yes I believe you can have an o/l relationship to explore bdsm (or your kinkier side) and maintain a vanilla r/l relationship. I have wrestled with this and have felt some guilt toward my r/l partner. After talking to others, the idea you must resolve is how (and if) your o/l relationship affects or detracts from your r/l relationship. Also you have to define what you consider cheating. I finally came to the conclusion that in an o/l relationship the touching is mental not physical, therefore I was not cheating. To many it's just a very creative form of masturbation. Only your conscience can decide how it works for you. My answer to this is I am happier and by exploring all aspects of my sexuality, I can enjoy all components of my love life.