A friend of mine I discussed your book “Preparation for a Lifetime” and asked me this question: “If on the night after your wedding your wife tells you that she’s HIV positive, what would you do”? I was dumbfounded for some time but later gave my own opinion anyway. What is your own opinion, sir?
Such things can happen, not just with HIV, but with other incurable sexually transmitted diseases, such as herpes. It could also happen with other secrets. I knew a young man who was devastated to find out a few months after his wedding that his wife had a child whom she never told him about -- worse, she had abandoned the child. He found out because she ran off and in the process of trying to find her, he found the child.
The reason most people council an engagement of at least a year is so that two people can learn about each other. Love is based on trust (I Corinthians 13:7; Proverbs 31:11). Such secrets can destroy the love developing in a marriage. It can turn a loving marriage into a nightmare.
What should a man do? First off, he made a covenant with his wife before God. As Solomon warns, "Do not be rash with your mouth, And let not your heart utter anything hastily before God. For God is in heaven, and you on earth; Therefore let your words be few. ... When you make a vow to God, do not delay to pay it; For He has no pleasure in fools. Pay what you have vowed - Better not to vow than to vow and not pay. Do not let your mouth cause your flesh to sin, nor say before the messenger of God that it was an error. Why should God be angry at your excuse and destroy the work of your hands?" (Ecclesiastes 5:2, 4-6). Even though the covenant was made without full disclosure, the covenant stands. This is illustrated by the Israelites. They made a covenant with the Gibeonites without checking out their story. They found out they were fooled, but they still honored the terms of their covenant (Joshua 9). It wasn't that the Gibeonites didn't suffer because of their lies. The covenant was a promise not to destroy them, so they ended up as slaves to the Israelites.
Second, having sex with this woman would be a danger to the man. I would strongly recommend that they stop having sex. It would be a grief to both of them, but a marriage vow doesn't mean a person jeopardizes his life. He survived without sex before his marriage, he can continue afterward.
Third, he is bound by his covenant until his wife dies. If she has HIV, she will most likely die long before he does. He is responsible for her care until that time. When she dies, he will be free to marry again, and hopefully he will choose more wisely.
I would feel sorry for both because it will be a loveless marriage. She must face the fact that this is what she gets for deceiving her husband. He must face the fact that he let his desire for a wife caused him to enter too hastily into a marriage covenant. Often a person has hints of possible problems in advance, but those hints are ignored. For instance, the man mostly likely knew the woman he was marrying wasn't a virgin. It would be prudent in an area where HIV is rampant to ask that she have herself checked for STDs and request to see the doctor's report. But some don't consider such things when they are infatuated with their bride-to-be.