1. The Chinuch (582) writes that during the first year of marriage (Shana Rishonah) the chosson should rejoice with his wife. He should not leave the city without her in order to fight in a war or for any other reason. The Chinuch concludes, “A chosson who leaves his kallah during the first year, even with her permission, has nullified a positive commandment. Yet, if he wishes to leave in order to fulfill a mitzvah or in order to rejoice with his friends for a few days, with the intention of returning, perhaps this is not nullifying a positive commandment. Some say that if the kallah gives permission he may leave.”
2. Many achronim forbid the chosson from leaving his wife during the shana rishonah, even if he is doing so for reasons of parnassah (see Binas Adam 129:37). Harav Ovadia Yosef zt”l rules stringently. However, if there is great need for him to leave or if he must leave for parnassah purposes, he may do so with his kallah’s permission (see Yalkut Yosef Nisuin page 237).
3. The Minchas Chinuch notes that this ruling of the Chinuch cannot be found in the works of other rishonim. (see also Chasam Sofer E.H. 2:155) Based on this assumption, some poskim did permit the chosson to leave during the first year, especially if the kallah grants him permission (see Radvaz 1:238 and Kitzur Shulchan Aruch 149:13). However, it seems that the common custom is to rule stringently.
4. The Chasam Sofer maintains that even the Chinuch would permit the chosson to leave in order to learn Torah.
5. The custom among Belz Chassidim is that the chosson does not serve as a chazzan during the shana rishonah. (Nisuin Kesidram 316)
6. Many do not wear a kittel during the shana rishonah (see Maharam Shick 28 and Ketzei Hamateh 619:11). The custom of Square Chassidim is not to wear the kittel on Pesach during the shana rishonah. The custom of Chabad Chassidim is not to wear the kittel on Yom Kippur during the shana rishonah. A similar ruling is expressed by Harav Yosef Greenwald zt”l of Pupa and Harav Yekutiel Yehuda Halberstam zt”l of Sanz Kloisenberg.
7. Others maintain that it is preferred to wear the kittel during the shana rishonah. Vizhnitz, Nadvorna, Sanzer, and Munkatch Chassidim wear the kittel during the shana rishonah.