TSB 90.3
(Testimonies on Sexual Behavior, Adultery, and Divorce 90.3)
Whatever have been the little sins indulged [they] will ruin the soul, unless they are overcome. The small sins will swell into the greater sins. Impure thoughts, private, impure actions, unrefined, low, and sensual thoughts and actions in the marriage life, the giving of loose reins to the baser passions under the marriage vow, will lead to every other sin, the transgression of all the commandments of God. (TSB 90.3) MC VC