I could never advise someone to pursue a romantic and/or sexual relationship with his wife’s sister. Acting on this impulse and desire you have can only lead to a world of grief for everyone involved. If you are unhappy in your marriage, get help to fix it, or get out. Only then pursue other options with other women, possibly including your wife’s sister, if she is available at that time.

The only way to navigate safely through the treacherous waters you find yourself in, is to sort out friendship from both romance and sex. The skill needed is to be able to sublimate any sexual energy aroused by your interaction with your wife’s sister, so that energy is moved up away from the genitals to the heart chakra, where it can be safely experienced as affection, friendship and non-sexual love rather than experienced as sexual desire.

Doing basic squeezing of the genital muscles (as if you were stopping the flow of urine mid-stream), while visualizing the energy moving up the spinal column to the crown of the head, then flowing down the front of your body to the heart (the center point between the nipples), can help accomplish this sublimation of sexual energy and its transformation into unconditional non-sexual love.