Ramayana was composed in the post-Vedic period, which predates Puranic period.
The wedding of Sita and Sri Rama was mentioned in Bala Kanda.
इयं सीता मम सुता सहधर्मचरी तव || १-७३-२६ प्रतीच्छ चैनां भद्रं ते
पाणिं गृह्णीष्व पाणिना |
"This is Seetha, my daughter, she acquits herself in whatever duty
you undertake. Take her wishfully, let safeness ...