After his sins became public he remembers weeping in brokenness and shame while flying from East Africa to the United States without his wife. Missionaries are tempted just like all other people. Living in and adapting to a new cultural setting, however, makes them more vulnerable to sin. At a latter stage of adaptation they can become discouraged by the lack of response, continued inability to communicate, and interpersonal conflict with teammates. Discouraged missionaries are more susceptible to sin.
Some cultures overtly parade certain types of sins to which the missionary is vulnerable.
The loss of vision frequently creates an environment where missionaries are vulnerable to Satan's attacks. Missionaries tend to be people of great vision. But sometimes this vision is rooted more in human ego than divine direction. They lose their vision for God's work and begin to think about worldly things. Thus discouragement breeds sin, and humanly-contrived visions die for lack of divine impetus.