https://en.wikipedia.org/wiki/Menachem_Creditor
R'Shlomo Carelbach did some nice things and made some terrible conclusions about Judaism. His music helped bring Jews closer to appreciating Judaism. However, when he started men and women dancing together from this music and not ashamed of this change, he is considered to have done something terrible. This may resulted in this marriage.
Rabbis have said that the sin of of the golden calf created by erev rav (converts from egypt who genuinely didn't want to be Jews) attracted many of the former slaves because of mixed gendered dancing...which led to their demise in the end.
Rabbi Carlebach wouldn't have been happy with this marriage. However, he would have realized in God's infinite wisdom that this sin of encouraging mixed dancing to bring Jews in to the fold was measure for measure of this marriage.