Love is always associated with adversity (bala):
They asked Sumnun: “Why has love always been bound up together with adversity (balā)?” He replied, “It is so that each and every ignoramus will not lay claim to love, and being confronted with adversity, they are forced to retreat.” (Tadhkirat al-awliya, 513)
Hadhrat Imam-i Rabbani Mujaddid-i Alf-i Sani (r.a) writes:
Maktubat-i-Imam-i-Rabbani, Vol.1, Part 3. Letter No.140.