Madhav is another name of the Supreme Divine Personality Shri Krishna. The meaning of 'Madhav' is 'Master of Yogmaya'.
Yogmaya is the name of the bliss yielding energy of Shri Krishna. This bliss yielding energy is Shri Radha as one who is worshipped and loved by the Supreme Lord Shri Krishna (Madhav) as She is the source of this bliss.
However, Shri Radha and Shri Krishna are in fact one!
joi radha soi krishna haim, in a mem bheda na mana,
ika haim hladini sakti aru saktimana ika jana - Bhakti Shatak.
(Meaning: Shri Krishna is the inseparable form of Shri Radha and Shri Radha is the inseparable form of Shri Krishna. Shri Radha is the Hladini Sakti (Bliss Potency) and Shri Krishna is the possessor of this energy)
The Supreme Personality Shri Krishna becomes Shri Radha Krishna in the field of Divine pastimes. These pastimes are eternal as the forms of Shri Radha and Krishna are also eternal.
Shri Radha Madhav ki Jai!
H.H. Dr Bageeshwari Devi