Kamasutra 5.4.60

5.4.60

sva-bhāryāṃ vā mūḍhaṃ prayojya tayā saha viśvāsena yojayitvā tayaivākārayet. ātmanaś ca vaicakṣaṇyaṃ prakāśayet. sā bhāryā-dutī[6] tasyās tayaivākāra-grahaṇam.

(6) When a man gets his wife to gain the confidence of a woman whom he wants to enjoy, and to call on her and talk to her about the wisdom and ability of her husband, that wife is called a wife serving as a go-between. In this case the feelings of the woman with regard to the man should also be made known through the wife.