Thyagaraja swamy's song Seetha Kalyana Vaibhogame defines qualities of rAmA, that makes him the best choice for Seetha and hence sung in all marriages.

rAmA is the best of brahmacharis, with charming eyes & physique, strong, dark, handsome, skilled, full of gentle love like kAmA, extremely powerful yet very humble, who can stand firm like mount meru for his devoted (wife), can annihilate mountain of evil that comes in the way of life.

The qualities of rAmA like skilled, powerful, humble, full of love are in no way different from the expectations of modern women. In that way, the song defines the qualities needed for men, even in modern marriage.

Hanuman is the best of Brahmacaris. Rama is praised by Hanuman himself. So he is the best of best brahmcari. Rama comes from a great lineage of people, with eyes like sun and moon and a charming physique.

To save those devoted, he deploys his arrows as net, helps them to enjoy and detach (as seen from the way he protected visvamitra's Yajna). So Seetha's choice is a trustable ally with great skill to protect her.

Though he is strong (bhima) to eliminate sinners, he is gentle like kAmA, full of love. This resident of Ayodhya is strong, dark and handsome (attracts all). Seetha's choice is a handsome lover.

Great warrior who can hold the entire world, yet humble with no pride, he is firm like Meru. Seetha's choice is humble and a great warrior who will stand like a mountain with her.

His form (attributes) is exactly as defined in scriptures, which can break mountains of evil to save his devoted. Seetha's choice is one who can go to any extent to protect her.

Thyagaraja worships this greatest of human being, rAmA with such great qualities, which is same as singing praise of the 'paramesa' to attain salvation.

rAmA praised by Hanuman, the best of brahmacaris is the best of best brahmachari. (rAmA roamed the forest with his beautiful wife still following his vows). He is from a great lineage, with charming eyes & physique, strong, dark, handsome, full of gentle love, skilled to protect his devoted, powerful to hold the world yet humble, stands firm like mount meru for his devoted, can annihilate mountain of evil that comes in the way of life, making him an ideal choice for Seetha.

Seetha Kalyana vaibhogame translation sung in tamil essence in english

https://www.youtube.com/watch?v=gvHBEZq9r78