Leaving Israel for my sister's Bat Mitzvah

Q: My family wants to celebrate my sister's Bat Mitzvah outside of Israel. Is it permissible to leave Israel to celebrate with them?
A: It is forbidden according to the Rambam (Hilchot Melachim 5:9), who writes that one may only temporarily leave to learn Torah, find a wife, or flee from non-Jews. Tosafot (Avodah Zarah 13b) allows leaving Eretz Yisrael for any mitzvah. But there is no mitzvah to celebrate a Bat Mitzvah outside of Israel. Do not lecture your family about it, simply say: I am sorry to say that I cannot come.