Sri Radha Ji & her divine immortal Love with Lord Sri Krishna is well recorded in Srimadbhagvatam & other Puranas. She had incarnated on earth during the time of Lord Krishna. Sri Radharani was a Gopi who was most near to Lord Krishna’s heart. Sri Radha's devotion and dedication towards Lord Sri Krishna was complete, that is the reason that she was most dear to Lord Sri Krishna. Goddess Shri Radha Rani took birth at a place called Barsana in Uttar Pradesh state in India. Goddess Sri Radha was the daughter of Vrishbhanu & her mother was Kirti.
Goddess Sri Radha was not married to Lord Sri Krishna but still she was most dear to Him even more than His wives. It was because, Sri Radha was always full of devotion towards the Lord & never thought of anyone else besides Lord Sri Krishna. In pictures Sri Radha is almost always depicted alongside Sri Krishna.
Sri Radha Rani is considered as the greatest devotee of Lord Sri Krishna. It is said that Sri Radha, herself is the "Devotional energy" of Lord Sri Krishna who is the Lord of the universe. Her name always comes before the name of Lord Sri Krishna that is why God's one name is "Radha Krishna" also. Just take out only one "R" from "Radha Krishna" & it becomes just "aadha Krishna" i.e. "half Krishna" & that is the power of the name "Radha". As Sri Radha Rani is always in the thought of Lord Sri Krishna the Supreme God, so her state of "Spiritual Emotion" is called "Maha Bhaav or महाभाव" i.e. the highest state of Spiritual Emotion or Spiritual Ecstasy.
As per the Bhagwat Gita, devotion is the easiest method to develop "Bhaav" & get close to the God. God himself declares about the glory of devotion in Bhagwat Gita:
"man-mana bhava mad-bhakto
mad-yaji mam namaskuru
mam evaishyasi satyam te
pratijane priyo ’si me" (Bhagwat Gita: Chapter Eighteen verse 65)
"Sri Krishna says to Arjuna: Always think of Me, become My devotee, worship Me and offer your homage unto Me. Thus you will come to Me without fail. I promise you this because you are My very dear friend."
mam ekam saranam vraja
aham tvam sarva-papebhyo
mokshayisyami ma suchah" (Bhagwat Gita: Chapter Eighteen verse 66)
"Sri Krishna says to Arjuna: Abandon all varieties of religion and just surrender unto Me. I shall deliver you from all sinful reactions. Do not fear."
"ye tu dharmamritam idam
bhaktas te ’tiva me priyah" (Bhagwat Gita: Chapter Twelve verse 20)
"Sri Krishna said to Arjuna: O Arjuna, Those who follow this imperishable path of devotional service and who completely engage themselves with faith, making Me the supreme goal, are very, very dear to Me."
"mayy eva mana adhatsva
mayi buddhim nivesaya
nivasisyasi mayy eva
ata urdhvam na samsayah" (Bhagwat Gita: Chapter Twelve verse 8)
"Sri Krishna said: O Arjuna, Just fix your mind upon Me and engage all your intelligence in Me. Thus you will live in Me always, without a doubt."
So let's have devotion in God. Let's remember God for some time in our daily life so that we too can generate some "Bhaav" or "Spiritual Emotion" towards the God. Once that is developed, we shall always find God near us & our life shall be filled with joy, love & ecstasy.