עשה רצונך כרצונו
- Ethics of the Fathers, Pirkei Avot

Your job as the confidant is usually not to persuade the future bride or groom to do things the way you see are right. It is to help them determine what they want in life, what they want from a spouose, and to assure them that the choice that is being made matches their own needs and their own desires, but they have expressed to you in confidence what they are looking for.

After all, the boy or the girl is going to have to live with the spouse and not you. So you should not try to convice them of your ideas. In other words, the spouse that you would want is not the issue here. It's the spouse that they would want and they have to clarify and understand what it is that they really deep down what they want and not what you would want so that they would be happy about taking the right step when they get married. This may be difficult for you. It is difficult to hold yourself back and not to offer ideas or suggestions about what you think would be right or wrong, but that is your job to restrain yourself, to simply determine what it is that they want and to clarify it, to make sure that you understand it exactly.

It may be difficult to find out the real things that they want. If they don't trust you enough then they will make statements or they will request a spouse who might be politically correct or who might be perceived by you as being the right one. If that is the case, then you are certainly doing them a disservice because they should be marrying the right person and not the person that is the one that you would want. It may take quite some time and effort to be able to determine a real list of what you want and what should be done, but that is the job that you should be doing.

Pirkei Avos, see above, says it best.