2:16 My beloved is mine, and I am his. This clearly expresses the sanctity of a monogamous relationship that is built on mutual love (cf. 6:3; 7:10).
MacArthur Study Bible
2:16 The possession of the loved one prefigures the possession of Christ and the church.
ESV Study Bible
2:16 My beloved belongs to me and I belong to him This statement—repeated in 6:3—reveals the intimate relationship between the man and woman. They belong to each other in a mutual giving of their love.
Faithlife Study Bible
2:16 he grazes among the lilies. In view of the context, this is most likely a metaphor for lovemaking.
Reformation Study Bible