Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
It is to be stressed first that Islam commands its followers to have good faith and trust towards the believers. Muslims are not supposed to harbor unnecessary suspicion without justification, as suspicion is indeed sinful. Therefore, if a wife's justification for losing her hymen is reasonable, as is the case in the question, the husband ought to believe her and there is no serious justification for divorce.
Here, is the fatwa issued by the European Council for Fatwa and Research, in response to the question in point:
“Divorce is a most despised permission that Allah has granted, and it is incorrect for a Muslim to resort to divorce for the slightest excuse, as divorce will break the woman's heart and destroy an entire Muslim family. In this case, there is no serious justification for divorce, particularly that the couple is at the first steps of married life. Indeed, it will lead to great harm affecting the woman and her reputation. Therefore, if the woman's justification is reasonable, as is the case in the question, the man ought to believe her. As it is possible that a woman may lose her hymen when practicing some sports and by being careless or even reckless with physical activities and so on. If the woman swore by Allah Almighty that she had never had a sexual relationship prior to the marriage, the man must believe her, as the famous legal principle is "proof is to be submitted by the accuser and an oath is to be made by the denying accused." The husband in this case is the accuser with no proof, while the accused, the wife, has sworn an oath denying the accusation, and thus, must be accepted. In any case, our Islamic dealing is based upon the principle of trust and good will towards people, as suspicion is indeed sinful. In the authentic Hadith reported by al-Bukhari and Muslim on the authority of Abu Hurayrah, the Prophet (peace and blessings be upon him) stated: "Beware of suspicion, as suspicion is the most false of address."
However, even if we assumed that the woman made a mistake in the past, then repented and returned to Allah, we know that Allah Almighty will accept her repentance and that this dissolves all her previous sins. Indeed, whoever repents from a sin is as though he has made no sin at all. Allah loves those who repent and loves the pure. It is upon us to adopt these descriptions and attributes of Allah Almighty and to forgive those who err, as all sons of Adam err, and the best of those who err are those who repent.
Excerpted, with slight modifications, from: http://www.ecfr.org/
