You wrote:
Let's try a simpler, clearer example. Consider a young 18 year old man with "raging hormones". He has been involved in fornication with his girlfriend and multiple others before her. He becomes a Christian and is repentant. He has a change of mind about his past behavior. I do not believe that if he continues to date his girlfriend, who is a willing sex partner, that his change of heart and mind would rule out any temptation.If the person would still be tempted, this is a clear indication that he has not had a change of heart and mind. He might have been sorry when he was caught, and some people call that "repentance" but he would not have repented as indicated by the Biblical word "μετανοια." "μετα" means "change" and "νοια" refers to the mind. Thus "μετανοια" means "change of mind." If the man had truly changed his mind about stealing, then he wouldn't be tempted when placed in the same position. If the employer is unable to trust him, then he did not truly forgive him.
The following is addressed to Christians who have presumably repented.
1 Corinthians 10:12 (NASB)
12. Therefore let him who thinks he stands take heed that he does not fall.
In the case I cited above, a change of relationship, I believe, is necessary.