Manava Dharmashastra 3.32

3.32

icchayā ca varasya kumāryāśca prītyā parasparasaṃyoga ekapradeśe saṃgamanam | tasyeyaṃ nindā maithunyaḥ kāmasambhavaḥ | mithunaprayojaneā 'maithunaḥ', tasmai hito maithunyaḥ | eṣa evārtho vispaṣṭīkṛtaḥ kāmasambhava iti | sambhavatyasmāditi sambhavaḥ, kāmaḥ sambhavo'syeti |

The mutual union of the bride and bridegroom, through love is to be known as the “Gāndharva” form; it has sexual intercourse for its end and it has its source in lust.—(32).

Medhātithi’s commentary (manubhāṣya):
The ‘union’—coming together at one place—‘of the bride and bridegroom, through love’—through mutual longing.

In deprecation of this form of marriage it is added—‘It has sexual intercourse for its end’—it serves the purpose of sexual intercourse only. This is made clearer by the next clause—‘it has its source in lust;’—‘source’ is that from which a thing springs; and it is from lust that this union springs.—(32).