Rabbeinu Bachay in Parshas Tzav says (second column sixteen lines from the bottom) that newlyweds bring a Korban Todah. He says that anyone that experiences a special joyous event should bring a Korban Todah, and in particular he says that a Chassan and Kallah should bring this korban. Most importantly, Rabbeinu Bachaya is telling us that when the passuk in Yirmiahu (33:11-12) says that people will once again bring the Korban Todah, it is referring to the beginning of the passuk that talks about the joy of the Chasan and Kallah, and the passuk means that Chassanim and Kallos used to- and someday soon will again bring- a Korban Todah.
I understand that the exuberant Chasan and Kallah would sing הוֹדוּ אֶת ה צְבָאוֹת כִּי טוֹב ה כִּי לְעוֹלָם חַסְדּוֹ. But the idea that Chasan and Kallah bring a Korban Todah is interesting, because we usually associate the korban with having survived some mortal danger. The Gemara (Brachos 54b, and see Rambam 10 Brachos 8 and OC 219:1) specifies four people who are obligated to bring this korban, and all are people who were saved from danger. In fact, this idea is reflected in our Tefilla. One who was saved from this type of danger makes the Bracha Birkas Hagomel. For general celebration, you can bring a shlamim or an olah, and the appropriate bracha is She'hechiyanu. So it's interesting that Rabbeinu Bachay says that a Korban Todah is brought to celebrate a joyous occasion. More importantly, why does Rabbeinu Bachay single out being newly married as the archetypal circumstance of bringing the Korban Todah?
Until someone is married, he is imprisoned by limited emotional horizons. He suffers from the astigmatism of egotism; he has no idea what it means to care for someone else more than he cares for himself, he lacks the basic understanding of what it means to be a fully realized human being, he is in danger of being emotionally stunted, a Wagnerian Nibelung. So, despite the Orwellian undertone, getting married really is like being liberated from prison.
As the Netziv says, the Korban Todah is brought על שנחלץ מצרה; literally, the word צרה means travail, but it is related to the word צר which means tight and constrained. So the best translation would be that the korban is brought on the occasion of "release from confinement." That is certainly an apt description of marriage. נחלץ מצרה means that he was granted expansion, an expansion that unbound him from his isolated strait.
That sentence deserves to be emphasized. על שנחלץ מצרה means that he was unbound from his strait of isolation. This is the foundation of the Korban Todah, and it is a perfect description of what marriage can give us.
As I mentioned above, the classic use of the Korban Todah is for a person that has has one of the following four experiences: These can be remembered with the mnemonic Chayim, חיים.. That is, Chavush/freed from prison; ; Yeshurim/recovered from illness; Yam/returned from an ocean voyage; and Midbar/returned from travel in the desert. Homiletically, one might say that all the elements of obligation for the Korban Todah are present when one gets married. He was a is a choleh, because if a person doesn’t get married, the Gemara says (Kiddushin 29b), he deteriorates physically (tipach.) He is like a traveler in the desert, as Hashem said that He remembers the love of our first relationship, when we followed Him into the desert, zacharti lach...lechteich acharai bamidbar, the willingness to risk everything because you love and trust your spouse.. He is like a prisoner freed from jail, because he has freed himself from the emotional prison of yechidus. And he is like one who has returned from a sea voyage, because after the long and lonely odyssey as he searched, he has finally come into his home port.
Note: Besides the Korban Todah, in the time of the Beis Hamikdash, a Chassan would come to the Beis Hamikdash especially on Shabbos, because on the east side of the structure there was a gate made of white glass through which only newlywed men would enter. When people would see a man come in through that gate, they would all bless him, saying "He Who dwells in this house, may he bless you with sons and daughters!" (From Pirkei D'Rebbi Eliezer 17. Although there is no mention of this gate in the Mishna in the first perek of Middos, which enumerates and describes all the entrances to the Beis Hamikdash, it is mentioned in Maseches Sofrim 19:12.) As it says in Pirkei D'Rebbi Eliezer, even though now we have no Beis Hamikdash, we should do the same when the Chassan comes to Shul on Shabbos.