From our Beit Midrash
Parashat Matot - Masei / Rav Eli Lewis
Flights overseas leaving Israel to Chutz Laaretz are common phenomena for both Israelis who travel on different ventures and non-Israelis who go back home after a year [or two] of Midrasha.
The Rambam writes that "it is forever forbidden to leave Eretz Yisrael to Chutz Laaretz with the exception of studying Torah or wedding a wife or saving Jews from the Goim – and then return to Israel".
The Ramban understands Rambam's sours to be from this week's Parasha in the words "and you shall inherit the land and dwell within it" – dwell within it and do not leave.
The Rambam himself holds that living in Chutz Laaretz may not necessarily be violating this Pasuk and the prohibition is leaving Israel more than living abroad. More so the prohibition is not on a Torah Level but rather only Rabbinic.
BTW this is one of the main reasons the Lubavicher Rebbi never visited Israel, he held if he enters he could not leave.
Praiseworthy is he who can follow the simple meaning of the Pasuk of the Torah and just stay without leaving, however those who do need to leave should try fulfilling the three exceptions stated above – study Torah, get married or save Jews from assimilating into the non-Jewish world; but most importantly – "then return to Israel"