She praises him because he has brought her as her king to the house of wine (ESV: banquet house). This is not a winery as we would understand it today, but we should think of a house that is completely empty, standing somewhere in the field. It is a structure surrounded by a whole piece of land with no further habitation. They can be completely alone there. They can give themselves entirely to each other there without having to pay attention to whether someone will enter their house or call them.
4 Il m'a fait entrer dans la maison du vin; Et la bannière qu'il déploie sur moi, c'est l'amour.