Sufi and Bhakti poetry is love poetry. All poems have a 'beloved'. In different languages, the beloved goes by different names like 'yaar' (यार), 'dost' (दोस्त), 'sajan' (सजन), 'sanam' (सनम), 'saiyan' (सैयां), 'dholna' (ढोलना), 'saajan' (साजन), 'sajna' (सजना), 'piya' (पिया), 'preet' (प्रीत), 'preetam' (प्रीतम), 'piya' (पिया), 'pī' (पी), 'meet' (मीत), and so on.
In relation to the beloved, two concepts are emphasized: union and separation.
What is union? When we are in union with our beloved, we feel that everything is perfect; we feel peaceful & content. We feel that everything in our experience is exactly how it should be; we feel as if time has come to a standstill; we desire that this state of being should last forever.
What is separation? When we are separated from our beloved, we feel that something is wrong; we find faults with ourselves (something is wrong with me, or something is wrong with what I did in the past) or others (something is wrong with them, or something is wrong with what they did in the past) or the environment (something is wrong with the world); our mind is not at ease; we may not feel like eating or drinking; we may lose our sleep; we experience negative states of mind like anger or depression or hatred; we have a strong urge to be in union with our beloved.
Why do Sufi and Bhakti poets repeatedly describe union and separation? For two reasons.
In our day to day life, we face situations. Sometimes, 'I' want X and the Universe also presents X to me. In such situations, our state of mind is exactly the state of mind experienced when we are in union with our beloved, as described above. The same thoughts arise; the same feelings arise:
Sometimes, 'I' want X but the 'Universe' presents Y to me, where X and Y are different. In that situation, our state of mind is exactly the state of mind experienced when we are separated from our beloved, as described above. The same thoughts arise; the same feelings arise:
When we find ourselves in a state of mind corresponding to separation, is it possible to move to a state of mind corresponding to union? Yes! Basically, separation occurs when 'I' want X but the 'Universe' has presented Y to me where X and Y are different. So the solution is to let go of X and accept Y. That's it! :)
We can restate union and separation in terms of expectation and reality. If the gap (mismatch) between expectation and reality is large, we get traumatized. If the gap (mismatch) is small, we are mildly irked. And when the gap is zero, we are at peace. In other words, when expectations are perfectly aligned with reality, peace is experienced. Simple, isn't it? :)