1- Is such an act considered adultery?
2- If the man himself says that penetration actually did happen, but a condom that numbs was used, and there is still doubt in the woman, does she have to accept his claim?
3- If the man himself is in doubt and isn't sure whether penetration took place or not what is the ruling?
4- Now that both of them are regretful and such an action has taken place, are the two haram to each other forever?
Fornication and indiscriminate relationship with women is one of the biggest evils in the society that leads to a lot of irreparable damages. Based on this, this type of relationship is forbidden and strongly detested in Islam, and that is why Islam has ordered not to even get close to this ugly act and its introductory steps.
One of the conditions for adultery (in Islamic terms) to take place (that entails specific rulings such as lashes, being haram to each other forever, etc.) is penetration of the glans (where circumcision is done) of the man's organ and until penetration hasn’t taken place, although what they have committed is a grave sin, but it isn't considered adultery in Islamic/jurisprudential terms and the two don’t become haram to each other forever. But in the case of such penetration, according to the fatwa of most of the maraji’, the two will be haram and unlawful to each other forever.
Fornication and indiscriminate relationship with women is one of the biggest evils in the society that leads to a lot of irreparable damages. Based on this, this type of relationship is forbidden and strongly detested in Islam.
Almighty Allah says in theQur’an “…Nor come near to adultery; for it is a shameful deed and evil, opening the road to other evils.”
In this short statement, three important points are made:
I. It did not say to not commit adultery but it says: do not come near this shameful act. This explanation besides being an emphasis that the depths of it related are evil work (fornication) in most cases has introductory steps that gradually lead one to come near it. Gazing at opposite sex is one of it introductory steps; exposing the body and immodest dressing is another introductory step, seductive literatures, inappropriate films, immoral publication and centers for corrupt acts. Each and every one of these is regarded as an introductory step towards fornication.
In addition, being alone with a woman that is not one’s mahram (that is sitting of a man and a woman in secluded place all alone), is another cause of seduction. The abandoning of marriage and unnecessary stringency from both families of a couple who want to get married; all these contribute to “coming close to fornication” which has been forbidden in the above verse in a short and simple sentence. Each and every one of these steps has been treated separately as forbidden by the traditions.
ii. The statement,“it is a shameful deed and evil” contains the use of three words of emphasis (Inna and the use of past tense, and the term “evil”) portray the grievous nature of this sin.
iii. The further statement “it is a bad path”, is an expression of the reality, that this deed leads to the spread of other evils in the society.
One of the conditions for adultery (in Islamic terms) to take place (that entails specific rulings such as lashes, being haram to each other forever, etc.) is complete penetration of the glans (where circumcision is done) of the man's organ and until that hasn’t happened, although what the unlawful man and woman have done is a grave sin, it isn't considered adultery in Islamic/jurisprudential terms. And if the two, or one of them isn't sure whether complete penetration of the glans has actually taken place or not, they have to think that it didn’t and there is no need for verification of whether it actually happened or not. Rather, they should repent for the mistake they have made and shouldn’t speak of it to anyone except with their lord and keep their hope in Him and His grace and mercy, He will forgive them inshallah.
But if they are sure that penetration of the entire glans has taken place, according to the fatwa (i.e., verdict) of the majority of the maraji’, they will be unlawful to each other forever and can never get married to each other, even in the case of both of them becoming single again (e.g. through divorce from their respective spouses) and there is no difference between whether the man knew or was unaware of the fact that she had a husband, and there is also no difference between a woman who was married a permanent marriage or temporary one. However, according to Ayatullah Saane’i and the late Ayatullah Tabrizi, the woman will not become eternally forbidden to the adulterer.
 Adopted from Question 2688, Adultery with a Married Woman.
 Nijat al-Ibad (of Imam Khomeini), pg. 371, issue 10; Tawdih al-Masaa’il of the maraji’, vol. 2, pg. 472, issue 2403, Qum, The Office of Islamic Publications of the Islamic Seminary in Qum, 1383 (solar calendar).
 Through an inquiry from his office via phone.