She was in love with Arjuna. However, Balarama wanted to marry her to Duryodhana. Krishna suggested that Arjuna abduct her because Balarama would not change his mind. So it happened. Their son was Abhimanyu.
Subhadra and Balarama are worshiped together with Krishna in Puri, where Krishna is worshiped as the Lord of the universe, Jagannatha.