The Gemara in Berachos (6b) says that one who makes happy the Chosson and Kallah merits the blessing of success in his Torah learning. This is a very strange reward. Why is this the appropriate payment for bringing joy to a Bride and Groom?
Reb Avraham Pam zt”l explains that the purpose of marriage is to lead to the fulfillment and application of Torah. The simcha that we bring to the newlyweds is meant to propel and encourage them to pursue closeness and dedication towards Hashem and fulfilling his Torah. Thus, one who brings them this joy, is rewarded with the exact same thing in his own life!
I believe that this is hinted in an amazing Gematriya. Ish and Isha (איש אשה) equals 616. This is the exact same numerical value as HaTorah (התורה). This is because the purpose of marriage is to bring out Torah!