A couple of years ago, we hosted a guest for a Shabbos meal. At the end, we passed around benchers for Birkas HaMazon from our collection of benchers at weddings we attended. One guest looked at his bencher and said, “Hey, this was my wedding bencher!” Oops! We felt bad, as he was recently divorced. Subsequently, we removed any wedding benchers relating to couples who got divorced.
Many of the circumstances of the Giving of the Torah suggest an association between it and a marriage. The Gemara  says that Hashem suspended Har Sinai on top of Klal Yisrael. Some commentaries explain that this was the wedding chuppah (canopy) for the Jewish nation. The mountain was adorned with pretty flowers, as is the custom for a chuppah. Hashem was the Chosson, and Klal Yisrael was the Kallah. The gifting of the Torah was what effected the marriage. Hence, Shavuos represents the union of Klal Yisrael with Hashem.
However, the marriage “honeymoon” was seemingly short lived. Just forty days later, Moshe descended the mountain with the Luchos (Tablets). Upon seeing the Jewish people dancing around the golden calf, Moshe threw down the Luchos and smashed them!
The Gemara  says that the broken pieces of the first Luchos were placed in the Aron (Ark) along with the second Luchos which Moshe later brought down. The smashing of the Luchos is almost similar to a marriage that ended with divorce. Why is Hashem keeping the bencher from the wedding that resulted in divorce?
There are two additional Yomim Tovim which have an element of receiving the Torah: Yom Kippur, when Moshe came down with the second set of Luchos, and Purim, when Klal Yisrael “re-accepted” the Torah…out of love.  Why in Kiddush and Shemoneh Esrei do we refer to the Yom Tov of Shavuos as “Zman Matan Torah” – the time of the giving of the Torah? After all, that union was seemingly severed. Maybe we should put away the Zman Matan Torah bencher that has the wedding date of Shavuos and instead label Yom Kippur or Purim as Zman Matan Torah?
As Rav Gedaliah Schorr  explains, the fact that Hashem told Moshe to place the broken pieces of the first Luchos together with the second Luchos demonstrates that the smashing of the Luchos was not a divorce. It was just a reaction to a bad mess-up and Klal Yisrael had to repair the relationship.
Rav Wolbe  says people mistakenly think that Shalom Bayis – a peaceful relationship in a home – occurs when two people have the same opinions and feelings; they’re always on the same page. The true meaning of Shalom Bayis is when people with different opinions and feelings manage to make peace and harmony between themselves. For a couple to have Shalom Bayis means they are able to learn from each other, work out their differences, and thereby live happily together.
The Jewish nation had a lot of work to do in order to get back together with Hashem after the sin with the golden calf. Moshe was able to work with Klal Yisrael to help restore their connection with Hashem. The first Luchos were kept together with the second Luchos in the Aron because they demonstrated the growth of the relationship. The pieces of the first Luchos represent a reminder that our bond with Hashem was not permanently damaged because of Klal Yisrael’s bad behavior, but rather it became deeper and stronger because of it.
Although Yom Kippur and Purim have elements of Kabbalas HaTorah, we celebrate Matan Torah on Shavuos since the marriage truly was on Shavuos. The other events just mark times when the relationship was restored.
Rabbi Shmuel Kamenetsky once told me that each year we should experience Shavuos as a new Kabbalas HaTorah. It’s a time to focus on developing a deep internal connection with Hashem and with the Torah He gifted to us.
Everyone has their ups and downs. Sometimes we falter and fail. The fact that we celebrate Shavuos as Kabbalas HaTorah demonstrates that the bond which Hashem created with us on Shavuos is eternal and can never be severed. Whatever we might have done in the interim, Hashem always waits for us to repair the relationship. Thereafter, the area in which we failed will be placed alongside our subsequent achievement, just as the broken pieces of the Luchos were placed together with the second Luchos.
 Shabbos 88a
 Bava Basra 14b
 Shabbos 88a
 Ohr Gedalyahu Moadim; Shavuos p. 80
 Alei Shur Vol. 2