He issued a conditional divorce and based it on his wife’s intention

Firstly: 

Undoubtedly you made a mistake by uttering a threefold divorce. You should be cautious and not hasty, and you should avoid mentioning divorce in what you say, whether at times of anger or otherwise. 

Secondly: 

If the matter is as you described, and you said, “My wife will be thrice divorced if she said that to your wife,” meaning thereby that if your wife said it with the intention of causing separation between your friend and his wife, but your wife had no such intention, then divorce has not taken place, because the Prophet (peace and blessings of Allaah be upon him) said: “Each person will have but that which he intended.” Narrated by al-Bukhaari (1) and Muslim (1907). 

Whoever speaks the words of divorce in general terms but bases it on his intention, that will be accepted from him, so long as his wife does not refer it to the qaadi (judge). As to whether it should be accepted by the judge, there is a difference of opinion among the scholars. 

Whoever swears that he will divorce his wife if she does not enter the house, then claims that he meant it to be for a month, his statement that it was limited to a month should be accepted.  

Ibn Qudaamah (may Allaah have mercy on him) said: Imam Ahmad said concerning one who swears that she should not enter the house and says, I meant for a month, it should be accepted from him. End quote from al-Mughni (7/320). 

The intention in this case has put a limit to the general wording, and each person knows best what his intention is, and Allaah is watching all of that and nothing is hidden from Him. 

And Allaah knows best.