A medical checkup showed that he is infertile but it is treatable. Should he tell his fiancée?
Question

During the engagement period, I did a premarital health checkup, and the doctor told me that I am infertile, but there is a remedy for that. In order to save face, can I do the marriage contract without informing my fiancée, or is it essential to disclose it? I hope that you can advise.
Praise be to Allah.The fuqaha’ differed regarding infertility and whether it is a defect in the case of marriage. There are two opinions.
The first opinion is that it is not regarded as a defect. This is the view of the majority of scholars, except al-Hasan al-Basri (may Allah have mercy on him), who regarded it as a defect that necessitates annulment of the marriage. Ahmad regarded it as mustahabb for a man who is infertile to disclose the matter before marriage.
The second opinion is that any defect that could put one of the spouses off the other, and result in the objectives of marriage, such as compassion and affection, not being attained, as being a defect that necessitates giving the other spouse the option of annulling the marriage. This is what was stated by Ibn al-Qayyim (may Allah have mercy on him), and he cited evidence for that; some of the contemporary scholars agreed with him on that, including Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him); he thought that not producing offspring is a defect that necessitates giving the husband or the wife the option to end the marriage.
He (may Allah have mercy on him) said: The correct view is that a defect is anything that causes the objectives of marriage not to be attained, and undoubtedly some of the most important objectives of marriage are physical pleasure, looking after one another and producing children. If there is anything that prevents fulfilling these objectives, then it is a defect. Based on that, if [the wife] finds out that the husband is infertile, or he finds out that she is infertile, this is a defect.
End quote from ash-Sharh al-Mumti‘ (12/220).
We have stated before that this is the view that is most likely to be correct, as noted in the answer to question no. 43496 .
In the answer to question no. 111980 we noted that if a defect or illness is temporary, and there is the hope that it may be overcome, then it is not essential to inform a potential spouse of it.
But, taking into account the seriousness of this matter [which is not being able to have children], and the fact that having children is a basic objective of marriage, it is essential to be frank and inform them of the reality of the situation.
The individual should look at himself; if he would not be pleased if his wife concealed this defect from him, then what he should do is be frank and not conceal it from her. Let the man treat people as he would like them to treat him.
And Allah knows best.