Is there a time that a rabbi must wait after his wife dies before he is allowed to date again? Some members of the shul have started to date only a few months after the death of their partner and others think they should wait a year. Rabbi says that the congregation would not respect any rabbi that did not wait two years after the death of his wife and I’m wondering if there is halacha about this.

Shalom, Thank you for your question. First of all let me wish a good and long life to all. The halacha is that a man whose wife dies is forbidden to remarry until three festivals have passed (see Shulchan Aruch, Yoreh Deah 392,2). Passover, Shavu'ot and Succot are classified as "festivals" for this purpose. Rosh HaShana and Yom Kippur are not. Neither is Chanukah or Purim. There are certain exceptions that apply to this rule – and in a case where the man has not yet fulfilled the command to be fruitful and multiply (by having fathered at least one boy and girl), or he has young children, or he needs someone to care for him, then he may marry straight after the shiva days are over. Your rabbi who talked about waiting longer may perhaps be talking about an emotional "time-out" period he feels appropriate from a psychological point of view, or what is considered as normative in your community. In any event, from a purely halachic point of view, the law is as we wrote above. Blessings.