According to the mainstream opinion, the resurrection of the dead is the final stage and follows the messianic age, as we say in the Shabbat morning prayers: “There is none like You in this world… in the world to come (heaven, where the souls go after death)… in the messianic period… in the resurrection from the dead”. Although the Rambam opines that it could be beforehand, this is a minority opinion. In the messianic age there will not be any change in the laws of nature (even the miraculous scientific breakthroughs of the last century have evolved through natural and logical developments), and accordingly, there will obviously be marriage which is a religious obligation. As a matter of fact, anyone who learns the sources objectively knows that with the modern return of Israel to the Land and State of Israel, we are already in the messianic era, in the words of our rabbis, “there’s no difference between (the exile and) the messianic era, but only that (the Jews) will no longer be subservient to the gentile governments” (Shabbat 63a). The messiah himself comes only at the end of the era, according to the following stages (in this order): the flourishing of the Land of Israel (which for 2,000 years was barren and desert); the in-gathering of the exiles (today there are already 6,000,000 Jews who have returned to the Land of Israel, and statistically, within the next 15 years most (!) of the Jews will be in Israel for the first time since the exile of the 10 tribes about 2,700 years ago); the revival of the Sanhedrin (religious law will run the Jewish State- this and the following stages have yet to come, but already most of the children in Israel in 1st grade are enrolled in religious education, so the country is gradually becoming more spiritual); the rebuilding of the Third Temple in Jerusalem; the anointing of the King (Messiah, from the descendants of King David, Megilla 17b). The messianic era is exactly that- an era, which is slowly but surely taking place before our very eyes. Just as the first two stages have been fulfilled, there’s no reason to doubt that the last three phases (which are somewhat easier, less 'fantastic" and less dependent upon external factors) will also also come true in the relatively near future. I suggest you come to Israel and see for yourself, the fulfillment of the first stages of the prophecies of Isaiah, Jeremiah and Ezekiel.
With Love of Israel,
Rav Ari Shvat