Luv-Kush, Shubha-Labha, Siddhi-Riddhi are inseparable pairs of Vedanta. They signify that one cannot get one without the help of the other.
In Luv-Kush, Kush is a symbol of purity and Luv symbolise the spiritual love. To achive love one has to be pure in consciousnes. To acquire love and inner happiness in life one may has to use kush, a herb, in daily life. No traditional Hindu ritual is complete without the use of kush grasses.
Kush is a benevolent satwik detoxifying grass, a symbol of progress and alertness. The word “kushal buddhi” originates from the word kush. In Bhagwad Gita (shloka 6.10) Krishna said that for meditation one should sit on a seat covered with kush grass. The Garuda Purana also described the importance of kush grass in rituals of Panchak death and in cremation of a person whose body has not been found as in natural calamities, by making an effigy of kush grass and completing the rituals. Kush grass is often held in the hands before taking a sankalp. In Ayurveda Kush grass is called desmostactya bipinnata. It is a clean, pure, brittle grass with acrid, cooling, oleaginous, aphrodisiac, and diuretic properties. Kush ke sharbat is a routine drink used by traditional healers of Chattisgarh.
In Riddhi-Siddhi, Riddhi is knowledge and Siddhi the perfection. One attains obstacle free life (represented by Ganesha) only when one master or tame both knowledge and perfection. Riddhi and Siddhi were the two inseparable wives of Lord Ganesha. Others symbolize Siddhi as success and Riddhi as prosperity or Riddhi as material abundance and Siddhi as the intellectual and spiritual prowess or Riddhi as prosperity and Siddhi as progress. All are dependent on each other.
Ganesha is said to have two sons, Shubha-Labha, again the two terms are inseparable from each other. Both are written during Dewali on each accounts book. Shubha is auspiciousness and Labha the profit.
Ram Lakshman often spoken as Ram-Lakhan signifies that to be in touch with consciusness (Rama) one has to control the mind with an aim (Mana with a Lakshya).
Other pairs, which are inseparable, are the duals of Rama and Sita, Radha and Krishna, Shiva and Parvati, Brahma and Saraswati and Vishnu and Lakshmi.
In Rama Sita, Rama signifies soul consciousness and Sita as the body. It is true for the Krishma and Radha combination. They also signify the dual character of the nature, feminine and masculine natures.
In Brahma and Sarawsawti, as the dude, Brahma represents creativity or innovations and Saraswati the art of acquiring pure knowledge. Again both are dependent on each other.
Lakshmi and Vishnu are again inseparable. Vishnu or Krishna is the doer and performer. They signify the action in the present. Lakshmi signify the material and spiritual benefits. One can only get the benefits by action in dharma.
Shiva-Parvati is other inseparable word used in Vedic literature. The other is Shiva and Sakti. They represent the true nature of the consciousness, the male and the female energies; the purusha and the prakiti. In terms of computer language they represents the operational and the application software. No computer can run without both of them
Other uncommon pairs are Bharata and Shatrughana of Ramayana. Bharata represents bhakti, devotion and discipline and Shatrughana the victory over the enemy. To win over the Shatru one has to become Bharata.
The pairs of modern post Vedic era are Heer-Ranjha; Laila-Majnu, Sheeri-Farihad, Banti and Babli and Veeer-Jara. They all symbolize human love relationship.