I’m currently dating a girl and it is going well. Not long ago, she went out with a friend of mine multiple times. (I don’t know who ended it.) Is it okay to bring up his name on a date? I am afraid that marrying this girl will ruin my relationship with my friend and I want to be assured that she will be comfortable with me keeping him as a friend.
The best part of this question is your first sentence. Boruch Hashem it is going well for you with this young, and may it only continue that way.
Based on your usage of powerful words such as “afraid,” “ruin,” and “assured,” I am going to write my answer assuming you have a good reason to believe that something happened between your friend and this young woman which is creating your desire to address this potential concern. If that is not the case, I would hope that all parties would be able to move forward like mature adults, knowing that most of us end up marrying someone who has dated other people in the past, and there would be no reason at all to address her previously dating your friend.
While the situation you find yourself in is certainly one that requires some finesse, it is not that unusual of a predicament. Generally speaking, it is natural for good friends to have a fair amount of commonality – good friends often have gone to the same or similar schools, share some combination of similar family dynamics, personalities, interests, hashkafa’s and levels of frumkeit, and are often looking for similar things in a shidduch. As such, it is quite common for friends to both be redd to, and date, the same people. I have seen this with friends and relatives, and know of at least one case where two good friends had been separately redd to young women who were also good friends, and each one is married to the woman that the other had previously dated. Boruch Hashem they have wonderful marriages and are all still good friends.
That said, I think there are two issues to discuss here, the more important one actually relating to you and the person you are dating, regardless of what may happen with your friend.
As far as bringing up your friend’s name on a date for the purpose which you have detailed, that seems reasonable and understandable to me. As long as nothing completely inappropriate or horrible happened between your friend and the young woman you are dating, this young woman should understand that whatever happened between the two of them, there is nothing objectively wrong with him, and no reason for you not to continue your friendship with him. As well, if your friend is truly a good friend he will understand that although she was not right for him, she might be right for you.
If the young woman cannot appreciate this reality, that could be cause for significant concern, and if your friend cannot accept it, perhaps you may want to reevaluate the strength of the friendship. However, in the event that for some reason you cannot have both, please make sure to evaluate what is more important to you, keeping your friend or marrying this woman. Ultimately, the most important relationship you will have in your life will be the one you have with your wife.
That is actually the less important issue here for me. The far more important issue is how the topic is broached. There should be no reason for any details to be discussed whatsoever. Not now, and probably not ever. Even if you marry this young woman it is highly unlikely that there will ever be value in discussing the details of her dating your friend and why it ended/did not work out.
Whatever the reason was that your friend and the person you are dating moved on, clearly they decided that they were not compatible as husband or wife. When friends, both bachurim and young women, begin to to discuss details with each other, the smallest negative word or seed of doubt planted by an askance look can often tear apart an shidduch that is 100% fine. Whatever reason one’s friend gives for why it did not work out for them or why they did not/would not date the person you are dating/considering dating, it is their reason. Just because they have an objection does not mean that you should. You must think for yourself and make decisions based on your needs and what you want in a shidduch. It cannot be stressed enough how dangerous it is for friends to discuss any particulars of their dating life with each other, including even mentioning the name of the person they are dating.
All that needs to be said to this young woman is something along the lines of, “I understand that you previously dated my friend ploini. While it did not work for the two of you, I hope that will not be an issue for you in my continuing my friendship with him.” Again, if noting terrible happened, there should be no reason why she would object. You are simply asking her to appreciate the situation and be open to you maintaining your friendship with the young man she previously dated, despite what may have transpired between them. As far as having a similar conversation with your friend to address your concern, that is up to you, but it absolutely should not take place prior to an engagement, and probably not even until some time after a wedding.
B’ezras Hashem you will be matzliach in having these conversations b’shalom ub’shalva.