What is the comparison to a bachelor with a virgin?
Rashi citing Targum Yonasan: Like a bachelor dwells with a Besulah, so your children will dwell in you.
Radak: This is a pleasant, accepted matter, more than an old man who has Bi'ah with a virgin, or a bachelor who has Bi'ah with a Be'ulah. So Eretz Yisrael, as long as her children were in her, even though other nations dwelled in her, she was not called Be'ulah, for they were not accepted there, and their dwelling was not pleasant. It was like an elder with a virgin, or a bachelor with a Be'ulah. When Yisrael return to her, this is like a bachelor who has Bi'ah with a virgin.
Malbim: Yisrael's return to their land, will not be like returning to a land that was once desolate, i.e. like one who divorced his wife and remarried her. He is not a bachelor, and she is not a virgin. Rather, it will be like a bachelor who has Bi'ah with a virgin. The land will be in its good and beauty as if it was never desolate.
When is "Mesos Chasan Al Kalah"?
Sanhedrin 99a: (A Chasan rejoices seven days with his Kalah.) Yemos ha'Mashi'ach will be 7000 years for Yisrael - "Ken Yasis Elokayich." Hashem's day is 1000 years.)
Radak: It is during the days of the Chupah. Then they are called Chasan and Kalah. Their Simchah is greater then, for they are newly [wed]. So your G-d's Simchah will be over you for all days.
Malbim: Hashem's return to you will not be like returning to a nation that he was angry at them, i.e. like one remarries his divorcee. The love is not complete, and they do not rejoice and dance openly. Rather, it will be like a Chasan with a Kalah that he was never intimate with her, and was never angry at her. So Hashem will rejoice over you and make a new Bris, and you will not remember old afflictions.
